1. IRON-ALUMINIUM(Fe3Al) SUPERALLOY
Under the able guidance of Dr. Atikur
Rehman
ROHIT KHANDELWAL- 603/11
VIKAL MANWAL- 305/11
JAGDEEP SINGH- 594/11
RAJINDER SINGH – 614/11
GAURAV KUMAR PANDEY- 513/11
2. CONTENTS
• ABSTRACT
• INTRODUCTION
• APPLICATION & PROPERTIES
• MANUFACTURING PROCESS
• HIGH TEMPERATURE OXIDATION
• MORPHOLOGY
• RESULTS
• CONCLUSION
• REFERENCES
3. ABSTRACT
Fe3Al superalloy were manufactured through Powder
Metallurgy process. Microstructure and cyclic high
temperature oxidation behavior of IRON ALUMINIDES
have been investigated. Cyclic high temperature
oxidation tests were conducted on samples at peak
temperatures of 900oC for up to 5 thermal cycles at the
room temperatures. SEM was used to characterize the
morphology of the samples. The oxidation results
confirmed an improved oxidation resistance of samples
as compared to normal alloys. The relevant oxidation
mechanisms are discussed.
4. INTRODUCTION
For more than 50 years, Iron-Aluminum intermetallic has received special interest
because of their potentially high oxidation resistance at high temperature. They
offer a good alternative for use in automotive parts, chemical processing, and gas
turbine technologies since they possess a high melting point, high thermal
conductivity, excellent oxidation resistance, low density, and low cost.
Iron aluminides, based around the stoichiometric compositions of Fe3Al and Fe-Al,
offer excellent resistance to oxidation and sulphidation at high temperatures, with
low material cost and density than austenitic and ferritic stainless steels . They
contain enough aluminum to form a thin film of aluminum oxide (in oxidizing
environments) that is often compact and protective. They possess relatively high
specific strengths and suitable mechanical properties at elevated temperatures.
They have, therefore, undergone extensive development, in the recent past,
exclusively for high temperature applications. However, their potential use as
structural materials at elevated temperatures has been hindered by limited ductility at
room temperature and sharp drop in strength above 600°C.
5. Iron aluminides are receiving special attention because they have a good yielding
point between 600 and 800°C, and even up to 1000°C when they are alloyed with
low expansion fibers such as alumina (Al203).[7] The charpy impact energy is
satisfactory at room temperature, and, depending on the grain size, the FeAI(40
at.%) offers a yielding point between 250 and 600 MPa, which can be increased
with additions of Hf or B.[8] Also, ingot iron aluminides have a lower density (5.6 g/cm3)
compared that for stainless steels and some nickel-based alloys, and a
relatively high melting point (1237°C). Their main disadvantage is their poor
ductility at room temperature. In the last few years, some new processing routes
have been tried to improve their ductility [9] together with the addition of fibers and
some micro-alloying elements. The good oxidation resistance of these materials is based on
their ability to develop a protective alumina layer (AI2O3) on their surface in many high-
temperature environments. Because alloys based on FeS-AI and Fe-Al form Al2O3
during exposure to oxidizing gases, they typically display low oxidation rates when
compared to iron-based and other alloys that do not form alumina in similar
conditions. Recent studies on FeS-AI alloys containing 2 to 5 at.% and various minor
additions of oxygen-active elements have shown that their long-term oxidation
performance approximately matches that of FeCrAlY alloys and Ni-Al at 1000°C, but
it is inferior at 1200 and 1300°C.
6. • A Super-alloy, or high-performance alloy, is an alloy that exhibits several key
characteristics: excellent mechanical strength, resistance to thermal creep
determination, good surface stability and resistance to corrosion or oxidation.
The crystal structure is typically face centered cubic lattice. Examples of such
alloys are Hastelloy, Inconel, Waspalloy, Rene Alloy, Haynes alloys, Inco-alloy,
MP98T, TMS alloys, and CMSX single crystal alloys.
• Super Alloy development has relied heavily on both chemical and process
innovations. Super Alloys develop high temperature strength through solid
solution strengthening. An important strengthening mechanism is precipitation
strengthening which forms secondary phase precipitates such as gamma prime
and carbides. Oxidation or corrosion resistance is provided by elements such
as Aluminium and Chromium.
• The primary application for such alloys is in turbine engines, both aerospace
and marine.
9. Powder selection
Iron Powder and aluminum powder of 20µm were selected
30gms of each metal.
• Powder was weighed using a digital weighing machine
according to the stoichiometric coefficient and composition.
S.no Iron
Composition
Aluminum
composition
Weight of iron
(For 5gm
sample)
Weight of
aluminum
1. 0.55 0.45 3.583 1.416
2. 0.50 0.50 3.371 1.628
3. 0.45 0.55 3.143 1.856
10. Powder Mixing
• Mixing of powder was done in a porcelain dish with
a mortar and pestle.
• Mixing was done thoroughly for 150 minutes with
slow addition of methanol.
• Mixed powder was taken out from the mortar.
11. Powder Compaction
• Powder was compacted in the mounting machine.
• Cold compaction of powder was done at room
temperature and at 1.5atm.
• A binding agent Tri-ethylene Di-amine was used for
proper compaction.
12. Sintering
• Sintering was done for the compaction and
formation of a solid mass of material by heat
without melting it to the point of liquefaction.
• Sintering was done at 1173K for three hours in a
muffle furnace.
• After Three hours the furnace was
shut down and samples was left
to cool in the furnace itself.
13. Metallography
• Surface grinding was employed to produce a smooth finish on flat surface.
• Grinding was done on those samples which were not oxidized.
• Grinding was done on emery paper with increasing fineness number.
• Polishing is the most important step in preparing a specimen for microstructural
analysis.
• Polishing was done with iron oxide.
• Etching can help reveal hidden flaws or defects in a part or component before
submitting the sample to traditional destructive or nondestructive examination,
metallography, microscopy, or other analytical technique.
• Etching – nital (98% alcohol and 2% nitric acid)
14. High Temperature oxidation
• To Study the oxidation behavior of Fe-Al super alloy
samples were heated at high temperature.
• Three Samples with Different Compositions were
subjected to 1273K for 2 hours in a electric furnace.
• Samples were cooled in air for half hour and then
weighed.
• Samples were subjected to a total of 5 heating-
cooling cycles.
• The gain in weight is observed with respect to total
exposure time.
