2. Course Contents
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• Course Code : AT19401
• Syllabus
Unit 1 – Alloys and Phase Diagrams
Unit 2 – Heat Treatment
Unit 3 – Ferrous and Non-Ferrous Metals
Unit 4 – Non-metallic Materials
Unit 5 – Advanced Materials
3. Alloys and Phase Diagrams
• Constitution of alloys
– Constitution ?
• Establishment, foundation, creation, formation,
structure, organization, charter, bill.
• Some technical terms
– System – Combination of phases of components
– Phase – physically and chemically homogeneous
– Components – the elements in the system
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4. Constitution of alloys
• Alloy?
– Combination of two or more elements, of which
one of the element should be a metal in major
portion.
– Eg: Brass (Cu- Zn), Steel (Fe-C)
– Alloys find very wide application in the industry
than pure metals.
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5. Pure Metals
• High electrical conductivity
• High ductility
• Corrosion resistance
– Tensile strength
– Yield point
– Hardness
Improved by alloying
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6. Classification of Alloys
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• Pure metals
• A pure metal is not found in nature normally. Ore generally contains a
variety of metals in lesser quantities that are then extracted to make the
base metal "pure".
• Solid solutions
– An alloy in which the solute atoms are distributed
in the solvent matrix and has the same structure
of the solvent
• Intermediate phase
– Formed between two dissimilar elements having
widely divergent electrochemical properties
8. Solid Solution
• Substitutional
– Disordered (or) Random
• α –Brass
– Ordered (or) Regular
• Aluminium - Copper
• Interstitial
– Fe - C
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9. Hume-Rothery`s rule
of solid solubility
• Relative size
– Atomic size of solute and solvent differ < 15%
• Chemical affinity
– Electronegativity – similar between two metals
• Relative Valency
– Solvent and solvent have same valency
• Crystal type
– Should be similar for solute and solvent
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10. Phase Diagrams
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• Graphical representation of phases in the
system at various temperatures, pressures and
compositions.
• Constructed by using equilibrium conditions.
• Depending on the number of components
– Unary ( one component)
– Binary (two components)
– Ternary ( three components)
11. Gibbs Phase
Rule
• P + F = C + 2
• An equation which established a definite
relationship in a system between the number
of phases, the number of degrees of freedom
and the number of components.
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13. Binary Alloy Phase Diagrams
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• Widely in use
• Constructed when only two elements are
present in the alloy.
14. Classification of Binary Alloy
System
• (i) Components completely soluble in liquid
state
– Completely soluble in solid state (Isomorphous
system)
– Insoluble in the solid state – Eutectic system (I
Type)
– Partially soluble in the solid state – Eutectic
system ( II Type)
– Peritectic System
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15. Classification of Binary Alloy
System
• Transformation in solid state
– Eutectoid reaction
– Peritectoid reaction
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16. Isomorphous System
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• Two components are completely soluble in
both the liquid and solid states.
• Only one type of crystal structure exists for all
the compositions of components.
19. Eutectic System ( I - Type)
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• Metals are completely soluble in liquid
state and is entirely soluble in solid state.
• Eg: Bi – Cd, Pb – AS, Au- Si
23. Eutectic System ( I Type)
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24. Peritectic Reaction
• Less common binary alloy reaction.
• Two phases, one liquid and one solid which
are already present will interact at a fixed
temperature to produce an entirely new
phase
• Found in Silver-Platinum alloy
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28. Eutectoid Reaction
• In eutectoid reaction, one solid decomposes
into two different solids at constant
temperature during cooling.
• The difference between eutectic and
eutectoid transformation is that the phases
involved in the eutectoid reactions are either
solid solutions or intermediate phases.
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31. Peritectoid Reaction
• This is another solid state transformation in
which two solids react with each other and
form a third solid at a constant temperature
during cooling.
• The alloy systems which show the Peritectoid
reaction are Ni-Zn, Cu-Sn, Ni-Mo, Fe-Nb.
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34. Iron – Iron carbon equilibrium
diagram
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• Provides the basis for understanding the
properties and heat treatment of steel and the
effect of alloying elements in alloy steel.
• It is not a true equilibrium diagram but
considered as a equilibrium phase.
• Other names
– Fe-Fe3C diagram
– Iron – iron carbide equilibrium diagram
38. Austenite
• It is the solid solution of carbon
and/or other alloying elements
(Mn, Ni) in gamma iron.
• Tensile strength: 10500 kg/cm2
• Elongation: 10% in 50 mm
• Hardness Rockwell C 40
• Non-magnetic and soft
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39. Ferrite
• Ferrite is B.C.C iron phase with
very limited solubility for carbon
( maximum 0.025% at 7230C)
• Softest structure that appears in
Fe –C equilibrium diagram.
• Tensile strength : 2800 kg/cm2
• Elongation : 40% in 50 mm
• Hardness less than Rockwell C 0
or Rockwell B 90
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41. Cementite
• Cementite or iron carbide,
contains 6.67% carbon by
weight.
• Typically hard and brittle with
tensile strength approx. 350
kg/cm2 but has high
compressive strength.
• Hardest structure in iron-
carbon equilibrium diagram.
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42. Pearlite
• Its microstructure consists of
alternate lamellae of ferrite and
cementite.
• Product of austenite
decomposition by an eutectoid
reaction.
• Eutectoid mixture contains
0.8% carbon and is formed at
13330F (723C).
• Elongation 20% in 50 mm
• Rockwell hardness C 20
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44. Ledaburite
• Eutectic mixture of
austenite and cementite.
• Contains 4.3% carbon.
• Formed at about 11300C
(20650F)
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45. Classification of Iron
• Grey cast iron
• White cast iron
• Malleable cast iron
• Nodular cast iron
• Alloy cast iron
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46. Grey cast iron
• An alloy of carbon and silicon with iron.
• It contains C=2.5-3.8%, Si = 1.1-2.8%, Mn = 0.4-
1%, P = 0.15%, S = 0.10%.
• It has good fluidity
• Possesses lowest melting point of ferrous alloy.
• Possesses machinability better than steels.
• It has high resistance to wear and vibration
damping capacity.
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47. Grey cast iron
• Uses:
– Machine tool structures.
– Man hole covers
– Cylinder blocks for IC engines
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48. Malleable Cast Iron
• It is obtained from hard and brittle white cast
iron through a controlled heat conversion
process.
• Possess high yield strength, good wear
resistance and damping vibration capacity.
• Contains C =2-3%, Si=0.6-1.3%, Mn =0.2-0.6%,
P=0.15%, S=0.10%.
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50. Nodular Cast Iron
• Graphite appears as rounded particles or
nodules.
• Possess very good machinability, excellent
castability and wear resistance.
• Damping capacity intermediate between cast
iron and steel.
• Contains C =3.2-4.2%, Si = 1.1-3.5%, Mn = 0.3-
0.8%, P = 0.08%, S =0.2%.
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51. Nodular Cast Iron
• Uses
– Paper industry machinery
– Power transmission equipment
– Earth moving machinery
– Pipes
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52. White Cast Iron
• Derives its name from the fact that its freshly
broken surface shows a bright white fracture.
• It possesses excellent abrasive and wear
resistance.
• Under normal circumstances, it is brittle and
not machinable.
• Contains: C= 1.8-3.6%, Si = 0.5-2.0%, Mn= 0.2-
0.8%, P=0.18%, S = 0.10%.
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53. White Cast Iron
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• Uses
– For producing malleable iron castings
– For manufacturing those components parts which
require a hard abrasion resistant material.
54. Alloy Cast Iron
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• Contains one or more alloying elements in
sufficient amount.
• The commonly used alloying elements are
nickel, chromium, molybdenum, copper,
titanium, aluminium and vanadium.
• These alloying elements are used to improve
the mechanical properties, resistance to
corrosion, wear or heat.
55. Alloy Cast Iron
• Ni-resist cast iron
– Pump components handling
slurry,
– Liners and turbo chargers,
exhaust manifolds
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56. Alloy Cast Iron
• Ni-hard resist cast iron
– Large coal pulveriser
– Grinding balls
– Impellers of sand
pumps
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58. Classification of steel
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– Plain carbon steels (less than 2% carbon and
negligible amounts of other residual elements)
• Low Carbon (less than 0.3% carbon) – making valves,
gears, railway axles, small forgings.
• Med Carbon (0.3% to 0.6%) – spring clips, connecting
rods, cushion springs, etc.,
• High Carbon (0.6% to 0.95%) – chisels, wrenches, jaws
of vises, hacksaw, etc.,
59. Classification of steel
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• Low Alloy Steel – Nickel, chromium and molybdenum
• High Alloy Steel – Silicon steel, nickel steel,
molybdenum steel, etc.,
• Stainless Steels (Corrosion-Resistant Steels) – contain
at least 10.5% Chromium
• Tool Steels – developed to form, cut or otherwise
change the shape of a material into a finished or
semi finished product.
60. Assignment 1
• Slow cooling of plain carbon steels
– Transformation in eutectoid steel
– Transformation in hypoeutectoid steel
– Transformation in hypereutectoid steel.
Last Date: 16/02/2016
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