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IntroToMetallography.pptx

The document provides information on metallography and microstructure analysis. It defines key terms like metallography, microstructure, phases, constituents, grains, grain boundaries, and grain size. It then discusses how to properly prepare metallographic specimens, including cutting, mounting, grinding, and polishing techniques. Finally, it provides examples of microstructures of various metals like aluminum, copper, steels, and superalloys revealed through different etching techniques.

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George F. Vander Voort Buehler Ltd Lake Bluff, Illinois USA
Metallography is the study of microstructure, how it is produced by composition and processing control, and the relationship between microstructure, mechanical and physical properties, and performance or service behavior. To examine the microstructure, we must prepare specimens properly so that the true structure, free of artifacts due to preparation, can be observed and properly identified, measured and interpreted.
Microstructure is the structure of a suitably prepare specimen as revealed by a microscope Microstructure consists of phases and/or constituents. A phase is a physically homogeneous, mechanically separable portion of a material system. A constituent is a phase or combination of phases, which occurs in a characteristic configuration in an alloy microstructure.
Grains are individual crystals within a metal. Most metals are polycrystalline, that is, made up of many individual crystals, but some are “single crystals” and have no internal grain boundaries. Grain boundaries are interfaces separating adjacent grains where the orientation of the crystal lattice changes from that of one grain to that of the other. The orientation difference is large. Sub-grain boundaries exhibit a small misorientation across the boundary.
Grain size is the dimension of the grains or crystals in a polycrystalline metal exclusive of twinned regions and sub-grains, when present. Although grains are three-dimensional in space, the size is estimated on the two-dimensional plane-of-polish for a large aggregate of grains (to provide statistical precision).
5/16 Sieve 4 Sieve 8 Sieve 14 Sieve Separation of grains by sieving after liquid metal embrittlement of Brass in Hg 3.3 mm 3.3 mm 3.3 mm 3.3 mm
To see the true microstructure we generally will cut a specimen from a larger section (the specimen must be representative) in a manner to minimize damage; encapsulate the specimen in a polymeric resin; grain and polish the specimen with a damage-free surface; etch the specimen with a suitable reagent (non-cubic metals may be examined with polarized light unetched); and document the images.
Medium and large format Delta™ abrasive saws with wheels 10 to 18 inch diameter.
With the chop cutter the contact area, when cutting a round bar, is very small initially, increases to a maximum, then decreases to a point contact. Thus, the pressure varies through the cut. This reduces cutting efficiency and increases heat generation. Orbital cutting reduces this variation. When the wheel lifts out of the cut, coolant flows into the cut which reduces sectioning damage.
Great versatility and a multitude of optional features make IsoMet® precision saws one of the labs best tools. A wide range of blades, both consumable and non-consumable, are available.
Modern presses, such as the SimpliMet® family of presses, have built in heating and cooling systems. Cooling a thermosetting polymer back to near ambient temperature reduces or eliminates shrinkage gaps, which improves edge retention and minimizes contamination and bleed out problems.
Phenocure™ mounting compound Improperly carburized 8620 alloy (arrow points to gap) 500 X Epomet® mounting compound Borided 42CrMo4 alloy steel 1000 X
The decarburized surface of this heat treated specimen of 440A stainless steel cannot be measured accurately due to rounding; the specimen was not mounted (Fry’s Reagent).
Semi-automatic (left) or fully automatic (right) systems not only improve productivity but they produce much higher quality specimens with better edge retention and freedom from artifacts – consistently.
8 and 10” (200 and 250 mm) 12” (300 mm) • Z-Axis Removal Control; • Under-Bowl Cooling • Head Speeds 30,40,50,60,150 rpm • Complementary or Contra; • Fully Programmable
Magnetic disk systems introduce convenience in multiple-user labs while reducing platen inventory.
• Polycrystalline – shorter preparation times – higher surface area on the diamond particles provides more cutting points Monocrystalline Polycrystalline
Alumina suspensions are redefined by sol-gel MasterPrep alumina (0.05-µm particle size). Unlike calcined alumina suspensions, MasterPrep suspensions are totally free of agglomerates. It markedly outperforms all other alumina abrasives and has none of the problems associated with colloidal silica.
Surface deformation from abrasive sectioning (left side, see arrows) of commercial purity (CP) Ti, ASTM F 67, Grade 2 (UNS R50400), annealed at 1038 °C, revealed using modified Weck’s reagent and cross polarized light plus sensitive tint. Original image at 100X. The magnification bar is 100 µm long. Mechanical twins can be seen along the top surface (see vertical arrow) which may have been caused by the clamping pressure.
Sectioning damage at cut edges of fine silver (100% Ag) revealed by etching with 10% NaCN and 10% ammonium persulfate.
Residual damage from shearing 14-karat gold (58% Au) revealed by etching with 10% NaCN and H2O2 (30% conc).
Residual grinding damage in fine silver (100% Ag) revealed by etching with 10% NaCN and 10% ammonium persulfate.
Surface Abrasive/Size Load Lb. (N)/ Specimen Base Speed (rpm)/Direction Time (min:sec) CarbiMet® 120 (P120) SiC* 6 (27) 240 – 300/Comp. Until plane CarbiMet 240 (P280) SiC* 6 (27) 240 – 300/Comp. 1:00 CarbiMet 320 (P400) SiC* 6 (27) 240 – 300/Comp. 1:00 CarbiMet 400 (P600) SiC* 6 (27) 240 – 300/Comp. 1:00 CarbiMet 600 (P1200) SiC* 6 (27) 240 – 300/Comp. 1:00 Canvas 6- m diamond paste 6 (27) 120 - 150/Comp. 2:00 Billiard 1- m diamond paste 6 (27) 120 - 150/Comp. 2:00 MicroCloth ® 0.05- m alumina slurry 6 (27) 120 - 150/Comp. 2:00 Based on 1 ¼ mount size *Water cooled
Surface Abrasive/Size Load Lb. (N)/ Specimen Base Speed (rpm)/Direction Time (min:sec) CarbiMet paper 180, 240 or 320 (P180, P240, or P400) SiC, water cooled 6 (27) 240 – 300 Comp. Until plane UltraPol™ 9- m MetaDi® Supreme diamond suspension 6 (27) 120 – 150 Comp. 5:00 TriDent™ 3- m MetaDi Supreme diamond suspension 6 (27) 120 – 150 Comp. 4:00 ChemoMet ® 0.05- m MasterPrep™ alumina suspension 6 (27) 120 – 150 Contra* 2:00 Based on 1 ¼ mount size *Use contra only with low-speed heads (<100 rpm)
Surface Abrasive/Size Load Lb. (N)/ Specimen Base Speed (rpm)/Direction Time (min:sec) CarbiMet paper 240- (P280) grit SiC Water cooled 5 (22) 240 Comp. Until plane UltraPol cloth 9- m MetaDi Supreme diamond suspension 5 (22) 150 Comp. 5:00 TriDent cloth 3- m MetaDi Supreme diamond suspension 5 (22) 150 Comp. 4:00 TriDent cloth 1- m MetaDi Supreme diamond paste 5 (22) 120 Comp. 2:00 MicroCloth pad 0.05- m MasterMet® Colloidal silica 5 (22) 120 Contra 1:30
Equiaxed alpha grains at the surface of a super-pure (SP) aluminum specimen etched with Barker’s reagent, 30 V dc, 2 min. Note the damage from sectioning along the surface (top edge); (polarized light + sensitive tint, 50X).
As-cast 206 aluminum (Al – 4.4% Cu – 0.3% Mg – 0.3% Mn) tint etched with Weck’s reagent and viewed with crossed polarized light plus a sensitive tint filter. Magnification bar is 50 µm long.
Wrought 2024-F aluminum (Al – 4.4% Cu – 1.5% Mg – 0.6% Mn) bar (28.5 mm diam.) showing the grain structure and intermetallics. Magnification bar is 200 µm long. Anodized with Barker’s reagent (30 V dc, 2 min.). Transverse plane.
6061-T6511 Keller’s Graff-Sargent NaF-NaOH Weck’s B&W – Bars are 20-µm long 500X Color is 200X
Weld Base Microstructure of a friction stir weld in 2519 aluminum (Al – 5.8% Cu – 0.3% Mn – 0.3% Mg – 0.06% Ti – 0.1% V – 0.15% Zr) etched with Weck’s reagent and viewed with polarized light plus sensitive tint. Original at 100X. The magnification bar is 100 µm long.
Surface Abrasive/Size Load Lb. (N)/ Specimen Base Speed (rpm)/Direction Time (min:sec) CarbiMet 320- (P400) grit SiC Water cooled 6 (27) 240 Comp. Until plane UltraPol Cloth 6- m MetaDi Supreme diamond suspension 6 (27) 150 Comp. 5:00 TexMet® 1500Pad 3- m MetaDi Supreme diamond suspension 6 (27) 150 Comp. 3:00 TriDent Cloth 1- m MetaDi Supreme diamond suspension 6 (27) 120 Comp. 2:00 MicroCloth Pad 0.05- m MasterMet Colloidal silica 5 (22) 120 Contra 2:00
Microstructure of hot extruded, cold worked and annealed (500 °C) high- purity copper etched with klemms III and Beraha’s PbS tint etches and viewed with polarized light plus sensitive tint, 46 HV. Klemm’s III Beraha’s PbS 100 µm 100 µm
As-Cast, Klemm’s II Wrought, Beraha’s PbS Microstructure of as-cast and hot extruded and cold drawn (interior) phosphorous-deoxidized copper tint etched and viewed with polarized light plus sensitive tint. 200 µm 100 µm
Bright Field Nomarski DIC, Bar is 100 µm Microstructure of sand-cast Cu – 4% Sn etched with Beraha’s PbS tint etch revealing the dendritic cast structure. 63 HV. 200 µm 100 µm
Cu–30% Zn, HE, CR 50%, Annl. 704 °C – 30 min. Klemm’s III, Original at 50X Beraha’s PbS, Original at 50X Microstructure of wrought cartridge brass, Cu – 30% Zn, cold reduced 50% and annealed at 704 °C (1300 °F) – 30 min. producing a fully recrystallized, and grown, equiaxed FCC grain structure with annealing twins. Polarized light and sensitive tint.
100 µm 100 µm Bright Field Nomarski DIC Microstructure of Muntz Metal, Cu – 40% Zn, heated to 716 °C (1320 °F), held 1 h and water quenched producing still more beta phase (colored), of larger size, and with less preferred orientation. Nomarski DIC of this specimen tint etched with Klemm’s I reagent reveals the grain and twin structure in the un-etched alpha phase (not colored).
Wrought, solution annealed and aged beryllium copper, Cu – 1.8% Be –0.3% Co. Heat treatment: 790 °C (1454 °F), hold 1 h, oil quench, age at 315 °C (600 °F) for 2 h. Hardness 380 HV. Swab etched with equal parts ammonium hydroxide and hydrogen peroxide (3% conc.). Polarized light brings out the diffuse “criss-cross” markings due to the fine ’ precipitates. There is some over-aging at the grain boundaries where can be found. Original at 200X. Crossed polars + sensitive tint.
20 µm Polarized Light Nomarski DIC 1 martensite formed in fcc alpha phase in a Cu – 26% Zn – 5% Al shape memory alloy (both un-etched).
Surface Abrasive/Size Load Lb. (N)/ Specimen Base Speed (rpm)/Direction Time (min:sec) CarbiMet paper 240- (P280) grit SiC Water cooled 6 (27) 240 Comp. Until plane BuehlerHercules™ H Rigid grinding disk 9- m MetaDi Supreme diamond suspension 6 (27) 150 Comp. 5:00 TriDent cloth 3- m MetaDi Supreme diamond suspension 6 (27) 150 Comp. 3:00 MicroCloth pad 0.05- m MasterPrep alumina suspension 6 (27) 120 Contra 1:30
Line Pipe Alloy Coated with Three Layers of Polymer for Protection from Sea Water Corrosion (Klemm’s I reagent, polarized light).
Ferrite grains in lamination sheet steel revealed using Klemm’s I tint etch. This is a duplex condition where there are much larger grains near the surface. Magnification bar is 100 µm in length (polarized light plus sensitive tint). Mount
Twinned austenitic grain structure of wrought, annealed Fe – 39% Ni color etched with Beraha’s sulfamic acid solution (100 mL water, 3 g potassium metabisulfite, 2 g sulfamic acid) and viewed with polarized light plus sensitive tint, 100X.
Twinned austenitic grain structure of solution annealed, wrought Hadfield manganese steel (Fe – 1.12% C – 12.7% Mn – 0.31% Si) tint etched with Beraha’s sulfamic acid reagent (100 mL water, 3 g potassium metabisulfite and 2 g sulfamic acid) and viewed with polarized light plus sensitive tint, 100X.
Upper bainite (blue and white) and as-quenched martensite (brown) in 5160 alloy steel (Fe – 0.6% C - 0.85% Mn – 0.25% Si – 0.8% Cr) that was austenitized at 830 °C (1525 °F) for 30 min., isothermally held at 538 °C (1000 F°) for 30 sec to partially transform the austenite, and then water quenched (untransformed austenite forms martensite). Etched with aqueous 10% Na2S2O5.
Low-carbon, “lath” martensite in an over-austenitized specimen of AerMet 100 (Fe – 0.23% C – 13.4% Co – 11.1% Ni – 3.1% Cr – 1.2% Mo). The grain size was coarsened by the heat treatment (1093 °C, AC, age at 675 °C for 6 h, AC) making it easier to see the lath structure. Etched with aqueous 10% sodium metabisulfite and viewed with polarized light plus sensitive tint. Original magnification was 100X. AerMet is a trademark of Carpenter Technology Corp., Reading, Pennsylvania.
Example of “butterfly” martensite (low carbon martensite) formed on the polished surface of a specimen of High-Expansion 22-3 (Fe – 0.1% C – 0.5% Mn – 0.2% Si – 3.1% Cr – 22% Ni) alloy steel when cooled to –73 °C. Unstable austenite transformed to martensite with its characteristic shear which is visible on a free surface using Nomarski DIC ( not etched). 25 µm
Surface Abrasive/Size Load Lb. (N)/ Specimen Base Speed (rpm)/Direction Time (min:sec) CarbiMet paper 240- (P280) grit SiC Water cooled 6 (27) 240 Comp. Until plane UltraPol cloth 9- m MetaDi Supreme diamond suspension 6 (27) 150 Contra 5:00 TriDent cloth 3- m MetaDi Supreme diamond suspension 6 (27) 150 Contra 5:00 ChemoMet pad 0.05- m MasterPrep alumina suspension 6 (27) 120 Contra 2:00
Microstructure of Custom Flo 302-HQ austenitic stainless steel (Fe - <0.08% C – 18% Cr – 9% Ni – 3.5% Cu) in the hot rolled and solution annealed condition after tint etching with Beraha’s BI reagent. The structure is equiaxed, twinned FCC austenite. The faint vertical lines are from alloy segregation (longitudinal direction is vertical). Viewed with polarized light plus sensitive tint. The magnification bar is 100 µm long.
Microstructure of wrought 7-Mo duplex stainless steel (Fe - <0.1% C – 27.5% Cr – 4.5% Ni – 1.5% Mo) solution annealed and then aged 48 h at 816 °C to form sigma. Electrolytic etching with aqueous 20% NaOH (3 V dc, 10 s) revealed the ferrite as tan, the sigma orange, while the austenite was not colored. Magnification bar is 10 µm in length.
Dendritic microstructure of Alloy 718 in the as-cast condition after tint etching with Beraha’s reagent. Note the white particles are delta phase. The magnification bar is 200 µm long.
Microstructure of wrought, solution annealed and double aged (about 42 HRC) Waspaloy, a nickel-based superalloy (Ni – 0.06% C – 19.5% Cr – 4.2% Mo – 13.5% Co – 3% Ti – 1.35% Al – 0.07% Zr –0.005% B - <2% Fe) tint etched with Beraha’s BIV reagent revealing twinned austenitic grains. Viewed in bright field. The magnification bar is 100 µm long.
Surface Abrasive/Size Load Lb. (N)/ Specimen Base Speed (rpm)/Direction Time (min:sec) CarbiMet paper 240- (P280) grit SiC Water cooled 6 (27) 240 Comp. Until plane UltraPol cloth 9- m MetaDi Supreme diamond suspension 6 (27) 150 Comp. 5:00 TexMet 1500 pad 3- m MetaDi Supreme diamond suspension 6 (27) 150 Comp. 4:00 TriDent cloth 1- m MetaDi Supreme diamond suspension 6 (27) 120 Comp. 3:00 ChemoMet pad 0.05- m MasterPrep alumina suspension 6 (27) 120 Contra 2:00
Microstructure of pearlitic gray cast iron tint etched with Beraha’s CdS reagent. Original at 500X.
Microstructure of austempered ductile iron tint etched with Beraha’s CdS reagent containing large graphite nodules (arrow), bainite (blue and brown) and retained austenite (white) when viewed with polarized light plus sensitive tint. Original at 500X.
As-cast NiHard cast iron (Fe – 2.98% C – 0.64% Mn – 0.85% Si – 4.4% Ni – 2.34% Cr) containing cementite (white), retained austenite (light brown), manganese sulfides (gray particles) and plate martensite “needles” (light blue and medium blue) after tint etching with Beraha’s CdS reagent and viewing with polarized light plus sensitive tint, 1000X.
Surface Abrasive Load, lb. rpm Minutes Waterproof Discs 220-320-grit (P240-P400) SiC 3 (13 N) 150-240 (comp.) Until Plane TexMet 1500 Pad 9-µm MetaDi Diamond Paste* 3 (13 N) 150-240 (comp.) 5 TexMet 1500 Pad 3-µm MetaDi Diamond Paste* 3 (13 N) 150-240 (comp.) 3 TexMet 1500 Pad 1-µm MetaDi Diamond Paste* 3 (13 N) 150-240 (comp.) 2 ChemoMet Pad MasterPrep Sol-Gel Alumina 2 (9) 100-150 (comp.) 2 *Use water as the lubricant, but keep the surface relatively dry Comp. = complementary ( both the head and platen rotating counterclockwise)
For 18-karat gold alloys, and similar highly noble precious metals: it is necessary to use an attack-polish agent in the MasterPrep alumina abrasive step. Mix 10 mL of the attack-polish solution with 50 mL of MasterPrep alumina slurry. The attack-polish agent can be: H2O2 (30% conc.), or aqueous 5-20% CrO3, or aqueous 10% oxalic acid, etc.
Microstructure of as-cast pure ruthenium, as polished, viewed in polarized light plus sensitive tint revealing a mixture of equiaxed and columnar HCP grains and some small shrinkage cavities (black). The magnification bar is 200 µm long.
Bright Field Nomarski DIC Microstructure of Spangold, Au – 19% Cu – 5% Al, a new jewelry alloy using martensite formation to create a rippled effect (“spangles”) on the surface. The specimen was polished, heated to 100 °C for 2 minutes, and quenched in water to form martensite, which produces shear at the free surface. This roughness can be seen using Nomarski DIC without etching. The criss-crossed pattern is produced by forming martensite, polishing and then forming new martensite.
Microstructure of Spangold, Au – 19% Cu – 5% Al, a new jewelry alloy using martensite formation to create a rippled effect (“spangles”) on the surface. The specimen was polished, heated to 100 °C for 2 minutes, and quenched in water to form martensite, which produces shear at the free surface. This roughness can be seen using Nomarski DIC without etching. The criss-crossed pattern is produced by forming martensite, polishing and then forming new martensite. The magnification bar is 50 µm long.
Microstructure of Spangold, Au – 19% Cu – 5% Al, a new jewelry alloy using martensite formation to create a rippled effect (“spangles”) on the surface. The specimen was polished, heated to 100 °C for 2 minutes, and quenched in water to form martensite, which produces shear at the free surface. This roughness can be seen using Nomarski DIC without etching. The criss-crossed pattern is produced by forming martensite, polishing and then forming new martensite.
Microstructure of wrought sterling silver ( 92% Ag) revealed by etching with equal parts of ammonium hydroxide and hydrogen peroxide (3% conc.)
Microstructure of fine silver ( 100% Ag) revealed by etching with 10% NaCN and 10% ammonium persulfate.
Bright Field Polarized Light 14-karat gold (52% Au) prepared without attack polishing, etched with equal parts of 10% NaCN and hydrogen peroxide (30% conc.) and viewed with bright field and with polarized light.
Previous specimen of 14-karat gold examined with polarized light plus a sensitive tint filter. The color effect comes from the surface roughness created by the grain-contrast etch.
The 14-karat gold specimen after attack polishing and re-etching with 10% NaCN and H2O2 (30% conc.) revealing a “flat” etch.
14-karat gold, attack polished and etched with equal parts of 10% NaCN and H2O2 (30% conc.) and viewed with bright field and Nomarski DIC. Bright Field Nomarski DIC
18-karat gold (75% Au – 22% Ag – 3% Ni) after attack polishing and etching with equal parts of 10% NaCN and H2O2 (30% conc.).
Bright Field Nomarski DIC 18-karat gold (75% Au – 22% Ag – 3% Ni) after attack polishing and etching with equal parts of 10% NaCN and H2O2 (30% conc.) and viewed with bright field and Nomarski DIC.
As-cast Paliney 7 (35% Pd – 30% Ag – 14% Cu – 10% Pt – 10% Au – 1% Zn) etched with aqua regia revealing a dendritic structure.
Solution annealed and aged 44% Pd – 38% Ag – 1% Ni – 16% Cu etched with equal parts of 10% NaCN and 10% ammonium persulfate .
Solution annealed and aged 44% Pd – 38% Ag – 1% Ni – 16% Cu etched with a 10 to 1 mix of HCl and HNO3. This etch brings up the grain boundaries in the matrix phase. Note the lamellar nature of the second-phase constituent.
Surface Abrasive/Size Load Lb. (N)/ Specimen Base Speed (rpm)/Direction Time (min:sec) Carbimet paper 320- (P400) grit SiC Water cooled 4 (18) 240 Comp. Until plane Ultra-Pol cloth 9- m Metadi Supreme diamond suspension 4 (18) 150 Comp. 4:00 Texmet 1000 pad 3- m Metadi Supreme diamond suspension 5 (22) 120 Comp. 4:00 Microcloth pad 0.05- m Masterprep alumina suspension 6 (27) 120 Comp. 3:00
Microstructure of Resiten G7 glass silicone laminate composite viewed with Nomarski DIC. The magnification bars are 100 and 50 µm long, respectively (left and right).
Microstructure of a graphite-fabric reinforced polysulfone composite viewed with cross polarized light plus sensitive tint. The magnification bar is 100 µm long.
Microstructure of a fiberglass-reinforced polymer I beam viewed with Nomarski DIC. The magnification bar is 20 µm long.
Extensive mechanical twinning was observed in high-purity, electron- beam melted zirconium after hot working and cold drawing. Viewed in polarized light. Magnification bar is 100 µm long.
Microstructure of wrought pure hafnium, with an as-polished specimen viewed in polarized light plus sensitive tint, revealing an equiaxed alpha HCP grain structure. A few mechanical twins can be seen at the surface (yellow arrows). The magnification bar is 100 µm long. Surface Mount
Microstructure of a W – 27% Cu powder metallurgy composite material after hot isostatic pressing. The specimen was etched with Klemm’s III for 20 seconds and imaged with bright field. The magnification bar is 20 µm long.
Microstructure of Zn – 0.1% Ti – 0.1% Cu hot rolled to 6 mm thickness, in the as-polished condition (left), using polarized light, revealing elongated HCP grains containing mechanical twins. Some fine precipitates are present in the grain boundaries but are not clearly revealed. For comparison, the structure on the right is shown after etching with the Palmerton reagent and viewing with polarized light plus sensitive tint). The magnification bars are 50 µm long.
Microstructure of Cd – 20% Bi in the as-cast condition, unetched, viewed with polarized light (slightly off the crossed position) plus sensitive tint revealing cadmium dendrites of various orientation. The interdendritic consituent is a eutectic of Cd and Bi, but is too fine to resolve at this magnification. The magnification bar is 200 µm long.
Microstructure of wrought 99.98% magnesium etched with the acetic- picral reagent and viewed with crossed polarized light plus a sensitive tint filter. The magnification bars are 200 and 100 µm long, left and right, respectively.
Microstructure of as-cast Mg – 2.5% rare earth elements - -2.11% Zn – 0.64% Zr revealed using the acetic-picral reagent and viewed with polarized light plus a sensitive tint filter. The magnification bars are 100 and 50 µm in length, left and right, respectively. A few mechanical twins can be seen.
Surface Abrasive/Size Load, lbs./(N) Base Speed (rpm)/Direction Time (min:sec) CarbiMet paper 320-grit (P400) watercooled 6 (27) 240 Contra or Comp. Until Plane UltraPol Cloth (psa) 9-µm MetaDi Supreme 6 (27) 150 Contra 10:00 MicroCloth pad (psa) 0.05-µm MasterPrep (1 part H2O2, 30% conc, to 5 parts alumina) 6 (27) 150 Contra (head <100 rpm) 10:00 Do not use contra in step 3 if the head rotates >100 rpm, as the abrasive will be splattered all over the room
Microstructure of CP Ti, ASTM F 67, Grade 2 (UNS R50400; specimen was in the as-rolled condition) prepared using the three-step method and viewed with polarized light to reveal the grain structure. Magnification bar is 100 µm long. Note the mechanical twins in the grains (arrows).
Microstructure of CP Ti, ASTM F 67, Grade 2 (UNS R50400; specimen in the as- rolled condition) prepared using the three-step method (previous slide) followed by a 20 minute vibratory polish, and viewed with crossed polarized light to reveal the grain structure. Original image at 100X. Magnification bar is 100 µm long. Note the deformation twins (arrows).
Microstructure of a Ti- 0.2% Pd alloy (UNS R52400) prepared using the three- step method and viewed with crossed polarized light to reveal an equiaxed alpha grain structure. Magnification bar is 100 µm long. The area at the left shows heavy deformation twinning (arrow) from sectioning (the cut edge is off the field of view to the left).
Microstructure of as-cast Ti – 6% Al – 4% V prepared using the three-step method, etched with modified Weck’s reagent, and viewed with polarized light to reveal a coarse “basket-weave” alpha/beta matrix structure. The boundaries of several former beta grains can be seen. Magnification bar is 200 µm long.
Microstructure of CP titanium containing SiC fibers prepared using the three-step method for titanium. The structure was viewed with Nomarski DIC to reveal the minor height differences. The magnification bar is 100 µm long.
IntroToMetallography.pptx

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IntroToMetallography.pptx

  • 1.
    George F. VanderVoort Buehler Ltd Lake Bluff, Illinois USA
  • 2.
    Metallography is thestudy of microstructure, how it is produced by composition and processing control, and the relationship between microstructure, mechanical and physical properties, and performance or service behavior. To examine the microstructure, we must prepare specimens properly so that the true structure, free of artifacts due to preparation, can be observed and properly identified, measured and interpreted.
  • 3.
    Microstructure is thestructure of a suitably prepare specimen as revealed by a microscope Microstructure consists of phases and/or constituents. A phase is a physically homogeneous, mechanically separable portion of a material system. A constituent is a phase or combination of phases, which occurs in a characteristic configuration in an alloy microstructure.
  • 4.
    Grains are individualcrystals within a metal. Most metals are polycrystalline, that is, made up of many individual crystals, but some are “single crystals” and have no internal grain boundaries. Grain boundaries are interfaces separating adjacent grains where the orientation of the crystal lattice changes from that of one grain to that of the other. The orientation difference is large. Sub-grain boundaries exhibit a small misorientation across the boundary.
  • 5.
    Grain size isthe dimension of the grains or crystals in a polycrystalline metal exclusive of twinned regions and sub-grains, when present. Although grains are three-dimensional in space, the size is estimated on the two-dimensional plane-of-polish for a large aggregate of grains (to provide statistical precision).
  • 6.
    5/16 Sieve 4Sieve 8 Sieve 14 Sieve Separation of grains by sieving after liquid metal embrittlement of Brass in Hg 3.3 mm 3.3 mm 3.3 mm 3.3 mm
  • 7.
    To see thetrue microstructure we generally will cut a specimen from a larger section (the specimen must be representative) in a manner to minimize damage; encapsulate the specimen in a polymeric resin; grain and polish the specimen with a damage-free surface; etch the specimen with a suitable reagent (non-cubic metals may be examined with polarized light unetched); and document the images.
  • 8.
    Medium and largeformat Delta™ abrasive saws with wheels 10 to 18 inch diameter.
  • 9.
    With the chopcutter the contact area, when cutting a round bar, is very small initially, increases to a maximum, then decreases to a point contact. Thus, the pressure varies through the cut. This reduces cutting efficiency and increases heat generation. Orbital cutting reduces this variation. When the wheel lifts out of the cut, coolant flows into the cut which reduces sectioning damage.
  • 10.
    Great versatility anda multitude of optional features make IsoMet® precision saws one of the labs best tools. A wide range of blades, both consumable and non-consumable, are available.
  • 11.
    Modern presses, suchas the SimpliMet® family of presses, have built in heating and cooling systems. Cooling a thermosetting polymer back to near ambient temperature reduces or eliminates shrinkage gaps, which improves edge retention and minimizes contamination and bleed out problems.
  • 12.
    Phenocure™ mounting compound Improperlycarburized 8620 alloy (arrow points to gap) 500 X Epomet® mounting compound Borided 42CrMo4 alloy steel 1000 X
  • 13.
    The decarburized surfaceof this heat treated specimen of 440A stainless steel cannot be measured accurately due to rounding; the specimen was not mounted (Fry’s Reagent).
  • 14.
    Semi-automatic (left) orfully automatic (right) systems not only improve productivity but they produce much higher quality specimens with better edge retention and freedom from artifacts – consistently.
  • 15.
    8 and 10”(200 and 250 mm) 12” (300 mm) • Z-Axis Removal Control; • Under-Bowl Cooling • Head Speeds 30,40,50,60,150 rpm • Complementary or Contra; • Fully Programmable
  • 16.
    Magnetic disk systemsintroduce convenience in multiple-user labs while reducing platen inventory.
  • 17.
    • Polycrystalline – shorter preparation times –higher surface area on the diamond particles provides more cutting points Monocrystalline Polycrystalline
  • 18.
    Alumina suspensions areredefined by sol-gel MasterPrep alumina (0.05-µm particle size). Unlike calcined alumina suspensions, MasterPrep suspensions are totally free of agglomerates. It markedly outperforms all other alumina abrasives and has none of the problems associated with colloidal silica.
  • 20.
    Surface deformation fromabrasive sectioning (left side, see arrows) of commercial purity (CP) Ti, ASTM F 67, Grade 2 (UNS R50400), annealed at 1038 °C, revealed using modified Weck’s reagent and cross polarized light plus sensitive tint. Original image at 100X. The magnification bar is 100 µm long. Mechanical twins can be seen along the top surface (see vertical arrow) which may have been caused by the clamping pressure.
  • 21.
    Sectioning damage atcut edges of fine silver (100% Ag) revealed by etching with 10% NaCN and 10% ammonium persulfate.
  • 22.
    Residual damage fromshearing 14-karat gold (58% Au) revealed by etching with 10% NaCN and H2O2 (30% conc).
  • 23.
    Residual grinding damagein fine silver (100% Ag) revealed by etching with 10% NaCN and 10% ammonium persulfate.
  • 24.
    Surface Abrasive/Size Load Lb.(N)/ Specimen Base Speed (rpm)/Direction Time (min:sec) CarbiMet® 120 (P120) SiC* 6 (27) 240 – 300/Comp. Until plane CarbiMet 240 (P280) SiC* 6 (27) 240 – 300/Comp. 1:00 CarbiMet 320 (P400) SiC* 6 (27) 240 – 300/Comp. 1:00 CarbiMet 400 (P600) SiC* 6 (27) 240 – 300/Comp. 1:00 CarbiMet 600 (P1200) SiC* 6 (27) 240 – 300/Comp. 1:00 Canvas 6- m diamond paste 6 (27) 120 - 150/Comp. 2:00 Billiard 1- m diamond paste 6 (27) 120 - 150/Comp. 2:00 MicroCloth ® 0.05- m alumina slurry 6 (27) 120 - 150/Comp. 2:00 Based on 1 ¼ mount size *Water cooled
  • 25.
    Surface Abrasive/Size Load Lb.(N)/ Specimen Base Speed (rpm)/Direction Time (min:sec) CarbiMet paper 180, 240 or 320 (P180, P240, or P400) SiC, water cooled 6 (27) 240 – 300 Comp. Until plane UltraPol™ 9- m MetaDi® Supreme diamond suspension 6 (27) 120 – 150 Comp. 5:00 TriDent™ 3- m MetaDi Supreme diamond suspension 6 (27) 120 – 150 Comp. 4:00 ChemoMet ® 0.05- m MasterPrep™ alumina suspension 6 (27) 120 – 150 Contra* 2:00 Based on 1 ¼ mount size *Use contra only with low-speed heads (<100 rpm)
  • 26.
    Surface Abrasive/Size Load Lb. (N)/ Specimen BaseSpeed (rpm)/Direction Time (min:sec) CarbiMet paper 240- (P280) grit SiC Water cooled 5 (22) 240 Comp. Until plane UltraPol cloth 9- m MetaDi Supreme diamond suspension 5 (22) 150 Comp. 5:00 TriDent cloth 3- m MetaDi Supreme diamond suspension 5 (22) 150 Comp. 4:00 TriDent cloth 1- m MetaDi Supreme diamond paste 5 (22) 120 Comp. 2:00 MicroCloth pad 0.05- m MasterMet® Colloidal silica 5 (22) 120 Contra 1:30
  • 27.
    Equiaxed alpha grainsat the surface of a super-pure (SP) aluminum specimen etched with Barker’s reagent, 30 V dc, 2 min. Note the damage from sectioning along the surface (top edge); (polarized light + sensitive tint, 50X).
  • 28.
    As-cast 206 aluminum(Al – 4.4% Cu – 0.3% Mg – 0.3% Mn) tint etched with Weck’s reagent and viewed with crossed polarized light plus a sensitive tint filter. Magnification bar is 50 µm long.
  • 29.
    Wrought 2024-F aluminum(Al – 4.4% Cu – 1.5% Mg – 0.6% Mn) bar (28.5 mm diam.) showing the grain structure and intermetallics. Magnification bar is 200 µm long. Anodized with Barker’s reagent (30 V dc, 2 min.). Transverse plane.
  • 30.
  • 31.
    Weld Base Microstructure ofa friction stir weld in 2519 aluminum (Al – 5.8% Cu – 0.3% Mn – 0.3% Mg – 0.06% Ti – 0.1% V – 0.15% Zr) etched with Weck’s reagent and viewed with polarized light plus sensitive tint. Original at 100X. The magnification bar is 100 µm long.
  • 32.
    Surface Abrasive/Size Load Lb. (N)/ Specimen BaseSpeed (rpm)/Direction Time (min:sec) CarbiMet 320- (P400) grit SiC Water cooled 6 (27) 240 Comp. Until plane UltraPol Cloth 6- m MetaDi Supreme diamond suspension 6 (27) 150 Comp. 5:00 TexMet® 1500Pad 3- m MetaDi Supreme diamond suspension 6 (27) 150 Comp. 3:00 TriDent Cloth 1- m MetaDi Supreme diamond suspension 6 (27) 120 Comp. 2:00 MicroCloth Pad 0.05- m MasterMet Colloidal silica 5 (22) 120 Contra 2:00
  • 33.
    Microstructure of hotextruded, cold worked and annealed (500 °C) high- purity copper etched with klemms III and Beraha’s PbS tint etches and viewed with polarized light plus sensitive tint, 46 HV. Klemm’s III Beraha’s PbS 100 µm 100 µm
  • 34.
    As-Cast, Klemm’s IIWrought, Beraha’s PbS Microstructure of as-cast and hot extruded and cold drawn (interior) phosphorous-deoxidized copper tint etched and viewed with polarized light plus sensitive tint. 200 µm 100 µm
  • 35.
    Bright Field NomarskiDIC, Bar is 100 µm Microstructure of sand-cast Cu – 4% Sn etched with Beraha’s PbS tint etch revealing the dendritic cast structure. 63 HV. 200 µm 100 µm
  • 36.
    Cu–30% Zn, HE,CR 50%, Annl. 704 °C – 30 min. Klemm’s III, Original at 50X Beraha’s PbS, Original at 50X Microstructure of wrought cartridge brass, Cu – 30% Zn, cold reduced 50% and annealed at 704 °C (1300 °F) – 30 min. producing a fully recrystallized, and grown, equiaxed FCC grain structure with annealing twins. Polarized light and sensitive tint.
  • 37.
    100 µm 100µm Bright Field Nomarski DIC Microstructure of Muntz Metal, Cu – 40% Zn, heated to 716 °C (1320 °F), held 1 h and water quenched producing still more beta phase (colored), of larger size, and with less preferred orientation. Nomarski DIC of this specimen tint etched with Klemm’s I reagent reveals the grain and twin structure in the un-etched alpha phase (not colored).
  • 38.
    Wrought, solution annealedand aged beryllium copper, Cu – 1.8% Be –0.3% Co. Heat treatment: 790 °C (1454 °F), hold 1 h, oil quench, age at 315 °C (600 °F) for 2 h. Hardness 380 HV. Swab etched with equal parts ammonium hydroxide and hydrogen peroxide (3% conc.). Polarized light brings out the diffuse “criss-cross” markings due to the fine ’ precipitates. There is some over-aging at the grain boundaries where can be found. Original at 200X. Crossed polars + sensitive tint.
  • 39.
    20 µm Polarized LightNomarski DIC 1 martensite formed in fcc alpha phase in a Cu – 26% Zn – 5% Al shape memory alloy (both un-etched).
  • 40.
    Surface Abrasive/Size Load Lb. (N)/ Specimen BaseSpeed (rpm)/Direction Time (min:sec) CarbiMet paper 240- (P280) grit SiC Water cooled 6 (27) 240 Comp. Until plane BuehlerHercules™ H Rigid grinding disk 9- m MetaDi Supreme diamond suspension 6 (27) 150 Comp. 5:00 TriDent cloth 3- m MetaDi Supreme diamond suspension 6 (27) 150 Comp. 3:00 MicroCloth pad 0.05- m MasterPrep alumina suspension 6 (27) 120 Contra 1:30
  • 41.
    Line Pipe AlloyCoated with Three Layers of Polymer for Protection from Sea Water Corrosion (Klemm’s I reagent, polarized light).
  • 42.
    Ferrite grains inlamination sheet steel revealed using Klemm’s I tint etch. This is a duplex condition where there are much larger grains near the surface. Magnification bar is 100 µm in length (polarized light plus sensitive tint). Mount
  • 43.
    Twinned austenitic grainstructure of wrought, annealed Fe – 39% Ni color etched with Beraha’s sulfamic acid solution (100 mL water, 3 g potassium metabisulfite, 2 g sulfamic acid) and viewed with polarized light plus sensitive tint, 100X.
  • 44.
    Twinned austenitic grainstructure of solution annealed, wrought Hadfield manganese steel (Fe – 1.12% C – 12.7% Mn – 0.31% Si) tint etched with Beraha’s sulfamic acid reagent (100 mL water, 3 g potassium metabisulfite and 2 g sulfamic acid) and viewed with polarized light plus sensitive tint, 100X.
  • 45.
    Upper bainite (blueand white) and as-quenched martensite (brown) in 5160 alloy steel (Fe – 0.6% C - 0.85% Mn – 0.25% Si – 0.8% Cr) that was austenitized at 830 °C (1525 °F) for 30 min., isothermally held at 538 °C (1000 F°) for 30 sec to partially transform the austenite, and then water quenched (untransformed austenite forms martensite). Etched with aqueous 10% Na2S2O5.
  • 46.
    Low-carbon, “lath” martensitein an over-austenitized specimen of AerMet 100 (Fe – 0.23% C – 13.4% Co – 11.1% Ni – 3.1% Cr – 1.2% Mo). The grain size was coarsened by the heat treatment (1093 °C, AC, age at 675 °C for 6 h, AC) making it easier to see the lath structure. Etched with aqueous 10% sodium metabisulfite and viewed with polarized light plus sensitive tint. Original magnification was 100X. AerMet is a trademark of Carpenter Technology Corp., Reading, Pennsylvania.
  • 47.
    Example of “butterfly”martensite (low carbon martensite) formed on the polished surface of a specimen of High-Expansion 22-3 (Fe – 0.1% C – 0.5% Mn – 0.2% Si – 3.1% Cr – 22% Ni) alloy steel when cooled to –73 °C. Unstable austenite transformed to martensite with its characteristic shear which is visible on a free surface using Nomarski DIC ( not etched). 25 µm
  • 48.
    Surface Abrasive/Size Load Lb.(N)/ Specimen Base Speed (rpm)/Direction Time (min:sec) CarbiMet paper 240- (P280) grit SiC Water cooled 6 (27) 240 Comp. Until plane UltraPol cloth 9- m MetaDi Supreme diamond suspension 6 (27) 150 Contra 5:00 TriDent cloth 3- m MetaDi Supreme diamond suspension 6 (27) 150 Contra 5:00 ChemoMet pad 0.05- m MasterPrep alumina suspension 6 (27) 120 Contra 2:00
  • 49.
    Microstructure of CustomFlo 302-HQ austenitic stainless steel (Fe - <0.08% C – 18% Cr – 9% Ni – 3.5% Cu) in the hot rolled and solution annealed condition after tint etching with Beraha’s BI reagent. The structure is equiaxed, twinned FCC austenite. The faint vertical lines are from alloy segregation (longitudinal direction is vertical). Viewed with polarized light plus sensitive tint. The magnification bar is 100 µm long.
  • 50.
    Microstructure of wrought7-Mo duplex stainless steel (Fe - <0.1% C – 27.5% Cr – 4.5% Ni – 1.5% Mo) solution annealed and then aged 48 h at 816 °C to form sigma. Electrolytic etching with aqueous 20% NaOH (3 V dc, 10 s) revealed the ferrite as tan, the sigma orange, while the austenite was not colored. Magnification bar is 10 µm in length.
  • 51.
    Dendritic microstructure ofAlloy 718 in the as-cast condition after tint etching with Beraha’s reagent. Note the white particles are delta phase. The magnification bar is 200 µm long.
  • 52.
    Microstructure of wrought,solution annealed and double aged (about 42 HRC) Waspaloy, a nickel-based superalloy (Ni – 0.06% C – 19.5% Cr – 4.2% Mo – 13.5% Co – 3% Ti – 1.35% Al – 0.07% Zr –0.005% B - <2% Fe) tint etched with Beraha’s BIV reagent revealing twinned austenitic grains. Viewed in bright field. The magnification bar is 100 µm long.
  • 53.
    Surface Abrasive/Size Load Lb.(N)/ Specimen Base Speed (rpm)/Direction Time (min:sec) CarbiMet paper 240- (P280) grit SiC Water cooled 6 (27) 240 Comp. Until plane UltraPol cloth 9- m MetaDi Supreme diamond suspension 6 (27) 150 Comp. 5:00 TexMet 1500 pad 3- m MetaDi Supreme diamond suspension 6 (27) 150 Comp. 4:00 TriDent cloth 1- m MetaDi Supreme diamond suspension 6 (27) 120 Comp. 3:00 ChemoMet pad 0.05- m MasterPrep alumina suspension 6 (27) 120 Contra 2:00
  • 54.
    Microstructure of pearliticgray cast iron tint etched with Beraha’s CdS reagent. Original at 500X.
  • 55.
    Microstructure of austemperedductile iron tint etched with Beraha’s CdS reagent containing large graphite nodules (arrow), bainite (blue and brown) and retained austenite (white) when viewed with polarized light plus sensitive tint. Original at 500X.
  • 56.
    As-cast NiHard castiron (Fe – 2.98% C – 0.64% Mn – 0.85% Si – 4.4% Ni – 2.34% Cr) containing cementite (white), retained austenite (light brown), manganese sulfides (gray particles) and plate martensite “needles” (light blue and medium blue) after tint etching with Beraha’s CdS reagent and viewing with polarized light plus sensitive tint, 1000X.
  • 57.
    Surface Abrasive Load,lb. rpm Minutes Waterproof Discs 220-320-grit (P240-P400) SiC 3 (13 N) 150-240 (comp.) Until Plane TexMet 1500 Pad 9-µm MetaDi Diamond Paste* 3 (13 N) 150-240 (comp.) 5 TexMet 1500 Pad 3-µm MetaDi Diamond Paste* 3 (13 N) 150-240 (comp.) 3 TexMet 1500 Pad 1-µm MetaDi Diamond Paste* 3 (13 N) 150-240 (comp.) 2 ChemoMet Pad MasterPrep Sol-Gel Alumina 2 (9) 100-150 (comp.) 2 *Use water as the lubricant, but keep the surface relatively dry Comp. = complementary ( both the head and platen rotating counterclockwise)
  • 58.
    For 18-karat goldalloys, and similar highly noble precious metals: it is necessary to use an attack-polish agent in the MasterPrep alumina abrasive step. Mix 10 mL of the attack-polish solution with 50 mL of MasterPrep alumina slurry. The attack-polish agent can be: H2O2 (30% conc.), or aqueous 5-20% CrO3, or aqueous 10% oxalic acid, etc.
  • 59.
    Microstructure of as-castpure ruthenium, as polished, viewed in polarized light plus sensitive tint revealing a mixture of equiaxed and columnar HCP grains and some small shrinkage cavities (black). The magnification bar is 200 µm long.
  • 60.
    Bright Field NomarskiDIC Microstructure of Spangold, Au – 19% Cu – 5% Al, a new jewelry alloy using martensite formation to create a rippled effect (“spangles”) on the surface. The specimen was polished, heated to 100 °C for 2 minutes, and quenched in water to form martensite, which produces shear at the free surface. This roughness can be seen using Nomarski DIC without etching. The criss-crossed pattern is produced by forming martensite, polishing and then forming new martensite.
  • 61.
    Microstructure of Spangold,Au – 19% Cu – 5% Al, a new jewelry alloy using martensite formation to create a rippled effect (“spangles”) on the surface. The specimen was polished, heated to 100 °C for 2 minutes, and quenched in water to form martensite, which produces shear at the free surface. This roughness can be seen using Nomarski DIC without etching. The criss-crossed pattern is produced by forming martensite, polishing and then forming new martensite. The magnification bar is 50 µm long.
  • 62.
    Microstructure of Spangold,Au – 19% Cu – 5% Al, a new jewelry alloy using martensite formation to create a rippled effect (“spangles”) on the surface. The specimen was polished, heated to 100 °C for 2 minutes, and quenched in water to form martensite, which produces shear at the free surface. This roughness can be seen using Nomarski DIC without etching. The criss-crossed pattern is produced by forming martensite, polishing and then forming new martensite.
  • 63.
    Microstructure of wroughtsterling silver ( 92% Ag) revealed by etching with equal parts of ammonium hydroxide and hydrogen peroxide (3% conc.)
  • 64.
    Microstructure of finesilver ( 100% Ag) revealed by etching with 10% NaCN and 10% ammonium persulfate.
  • 65.
    Bright Field PolarizedLight 14-karat gold (52% Au) prepared without attack polishing, etched with equal parts of 10% NaCN and hydrogen peroxide (30% conc.) and viewed with bright field and with polarized light.
  • 66.
    Previous specimen of14-karat gold examined with polarized light plus a sensitive tint filter. The color effect comes from the surface roughness created by the grain-contrast etch.
  • 67.
    The 14-karat goldspecimen after attack polishing and re-etching with 10% NaCN and H2O2 (30% conc.) revealing a “flat” etch.
  • 68.
    14-karat gold, attackpolished and etched with equal parts of 10% NaCN and H2O2 (30% conc.) and viewed with bright field and Nomarski DIC. Bright Field Nomarski DIC
  • 69.
    18-karat gold (75%Au – 22% Ag – 3% Ni) after attack polishing and etching with equal parts of 10% NaCN and H2O2 (30% conc.).
  • 70.
    Bright Field NomarskiDIC 18-karat gold (75% Au – 22% Ag – 3% Ni) after attack polishing and etching with equal parts of 10% NaCN and H2O2 (30% conc.) and viewed with bright field and Nomarski DIC.
  • 71.
    As-cast Paliney 7(35% Pd – 30% Ag – 14% Cu – 10% Pt – 10% Au – 1% Zn) etched with aqua regia revealing a dendritic structure.
  • 72.
    Solution annealed andaged 44% Pd – 38% Ag – 1% Ni – 16% Cu etched with equal parts of 10% NaCN and 10% ammonium persulfate .
  • 73.
    Solution annealed andaged 44% Pd – 38% Ag – 1% Ni – 16% Cu etched with a 10 to 1 mix of HCl and HNO3. This etch brings up the grain boundaries in the matrix phase. Note the lamellar nature of the second-phase constituent.
  • 74.
    Surface Abrasive/Size Load Lb. (N)/ Specimen BaseSpeed (rpm)/Direction Time (min:sec) Carbimet paper 320- (P400) grit SiC Water cooled 4 (18) 240 Comp. Until plane Ultra-Pol cloth 9- m Metadi Supreme diamond suspension 4 (18) 150 Comp. 4:00 Texmet 1000 pad 3- m Metadi Supreme diamond suspension 5 (22) 120 Comp. 4:00 Microcloth pad 0.05- m Masterprep alumina suspension 6 (27) 120 Comp. 3:00
  • 75.
    Microstructure of ResitenG7 glass silicone laminate composite viewed with Nomarski DIC. The magnification bars are 100 and 50 µm long, respectively (left and right).
  • 76.
    Microstructure of agraphite-fabric reinforced polysulfone composite viewed with cross polarized light plus sensitive tint. The magnification bar is 100 µm long.
  • 77.
    Microstructure of afiberglass-reinforced polymer I beam viewed with Nomarski DIC. The magnification bar is 20 µm long.
  • 79.
    Extensive mechanical twinningwas observed in high-purity, electron- beam melted zirconium after hot working and cold drawing. Viewed in polarized light. Magnification bar is 100 µm long.
  • 80.
    Microstructure of wroughtpure hafnium, with an as-polished specimen viewed in polarized light plus sensitive tint, revealing an equiaxed alpha HCP grain structure. A few mechanical twins can be seen at the surface (yellow arrows). The magnification bar is 100 µm long. Surface Mount
  • 81.
    Microstructure of aW – 27% Cu powder metallurgy composite material after hot isostatic pressing. The specimen was etched with Klemm’s III for 20 seconds and imaged with bright field. The magnification bar is 20 µm long.
  • 82.
    Microstructure of Zn– 0.1% Ti – 0.1% Cu hot rolled to 6 mm thickness, in the as-polished condition (left), using polarized light, revealing elongated HCP grains containing mechanical twins. Some fine precipitates are present in the grain boundaries but are not clearly revealed. For comparison, the structure on the right is shown after etching with the Palmerton reagent and viewing with polarized light plus sensitive tint). The magnification bars are 50 µm long.
  • 83.
    Microstructure of Cd– 20% Bi in the as-cast condition, unetched, viewed with polarized light (slightly off the crossed position) plus sensitive tint revealing cadmium dendrites of various orientation. The interdendritic consituent is a eutectic of Cd and Bi, but is too fine to resolve at this magnification. The magnification bar is 200 µm long.
  • 84.
    Microstructure of wrought99.98% magnesium etched with the acetic- picral reagent and viewed with crossed polarized light plus a sensitive tint filter. The magnification bars are 200 and 100 µm long, left and right, respectively.
  • 85.
    Microstructure of as-castMg – 2.5% rare earth elements - -2.11% Zn – 0.64% Zr revealed using the acetic-picral reagent and viewed with polarized light plus a sensitive tint filter. The magnification bars are 100 and 50 µm in length, left and right, respectively. A few mechanical twins can be seen.
  • 86.
    Surface Abrasive/Size Load, lbs./(N) BaseSpeed (rpm)/Direction Time (min:sec) CarbiMet paper 320-grit (P400) watercooled 6 (27) 240 Contra or Comp. Until Plane UltraPol Cloth (psa) 9-µm MetaDi Supreme 6 (27) 150 Contra 10:00 MicroCloth pad (psa) 0.05-µm MasterPrep (1 part H2O2, 30% conc, to 5 parts alumina) 6 (27) 150 Contra (head <100 rpm) 10:00 Do not use contra in step 3 if the head rotates >100 rpm, as the abrasive will be splattered all over the room
  • 87.
    Microstructure of CPTi, ASTM F 67, Grade 2 (UNS R50400; specimen was in the as-rolled condition) prepared using the three-step method and viewed with polarized light to reveal the grain structure. Magnification bar is 100 µm long. Note the mechanical twins in the grains (arrows).
  • 88.
    Microstructure of CPTi, ASTM F 67, Grade 2 (UNS R50400; specimen in the as- rolled condition) prepared using the three-step method (previous slide) followed by a 20 minute vibratory polish, and viewed with crossed polarized light to reveal the grain structure. Original image at 100X. Magnification bar is 100 µm long. Note the deformation twins (arrows).
  • 89.
    Microstructure of aTi- 0.2% Pd alloy (UNS R52400) prepared using the three- step method and viewed with crossed polarized light to reveal an equiaxed alpha grain structure. Magnification bar is 100 µm long. The area at the left shows heavy deformation twinning (arrow) from sectioning (the cut edge is off the field of view to the left).
  • 90.
    Microstructure of as-castTi – 6% Al – 4% V prepared using the three-step method, etched with modified Weck’s reagent, and viewed with polarized light to reveal a coarse “basket-weave” alpha/beta matrix structure. The boundaries of several former beta grains can be seen. Magnification bar is 200 µm long.
  • 91.
    Microstructure of CPtitanium containing SiC fibers prepared using the three-step method for titanium. The structure was viewed with Nomarski DIC to reveal the minor height differences. The magnification bar is 100 µm long.