Microstructural study of lm-25

LM 25 is an alloy of Aluminum combined mainly with 6- 7.5 % silicon , 0.2% copper and other materials .
It is corrosion resistant and strong
Excellent weldability
Application ranges from marine, electrical, automobile , nuclear and Aerospace industries .
This seminar deals with properties of the material and microstructure of material using SEM & AFM.

1. GUIDED BY PRESENTED BY
AJIMSHA J M NIHAS NASSIR
ASST. PROFESSOR S7 ME
MESITAM M12U036
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2. CONTENT
INTRODUCTION
CHEMICAL COMPOSION
SAMPLE PREPARATION
SEM
PARTS AND WORKING OF SEM
AFM
PARTS AND WORKING OF AFM
COMPARISON STUDY
ADVANTAGE OF LM-25
CONCLUSION
REFERENCES
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3. INTRODUCTION
•LM 25 is an alloy of Aluminum combined mainly
with 6-7.5 % silicon , 0.2% copper and other
materials .
•It is corrosion resistant and strong
•Excellent weldability
•Application ranges from marine, electrical,
automobile , nuclear and Aerospace industries .
•This seminar deals with properties of the material and
microstructure of material using SEM & AFM.
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4. CHEMICAL COMPOSITION
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5. Sample preparation
600g of LM -25 were taken and melted in electrical
resistance furnace
N2 is used as a degasser
Graphite rod are used for stirring
Pour into the mould and cast is obtained
This is used as the sample
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6. Scanning Electron Microscopy
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7. SCANNING ELECTRON
MICROSCOPE (SEM)
A scanning electron microscope (SEM) is a type
of electron microscope
It images a sample by scanning it with a high-
energy beam of electrons in a raster scan pattern.
The electrons interact with the atoms of the
sample
It gives the information about the structures of
grain, composition, and other properties
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8. Components of SEM
Electron gun
Condenser Lens
Aperture
Scanning system
Specimen Chamber
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9. 9

10. 10

11. 11

12. AFM
Atomic ForceMicroscopy
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13. Parts of AFM
Laser–deflected off cantilever
Mirror–reflects laser beam to
photodetector
Photodetector–dual element
photodiode that measures
differences in light intensity and
converts to voltage
Amplifier
Register
Sample
Probe–tip that scans sample made
of Si
Cantilever–moves as scanned
over sample and deflects laser beam
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14. 14

15. Contact Mode
Non-Contact Mode
Tapping (Intermittent
contact) Mode
3 MODES OF AFM
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16. Contact mode
Measures repulsion between tip and sample.
Force of tip against sample remains constant.
Feedback regulation keeps cantilever deflection constant
Problems: excessive tracking forces applied by probe to
sample
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17. Non contact mode
Measures attractive forces between tip and sample
Tip doesn’t touch sample
Van der Waals forces between tip and sample is
decteced and gives the AFM image
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18. Tapping mode
Tip vertically oscillates between the sample surface
at a frequency of 50,000 to 500,000 cycles/sec.
Oscillation amplitude reduced as probe contacts
surface due to loss of energy caused by tip
contacting surface. And gives the AFM image of
the test specimen.
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19. property LM-25 Aluminium Steel
Density 2670 kg/m3 2730kg/m3 7750kg/m3
Melting Point615°C 660.3°C 1370°C
Elastic Modulus71 GPa 70.0GPa 190.3GPa
Tensilestrength280 mpa 714.0mpa 500 mpa
Percent
Elongation
5% 20% 17%
Hardness 120 BHN 100BHN 95 BHN
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COMPARISON STUDY

20. Advantages of LM-25
good corrosion resistance
•Excellent cast ability
•It is corrosion resistant and strong
•Excellent weldability
•Application ranges from marine, electrical,
automobile , nuclear and Aerospace industries
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21. product made from LM-25
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22. CONCLUSION
The micro structural studies shows that LM-25 posses
good corrosion resistance and mechanical properties
Posses excellent weldability
It found more application in the field of marine,
electrical, automobile , nuclear and Aerospace industries
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23. References
[1] Association of North America 1998, pp1-31
[2] T.V.S. Reddy, D.K. Dived, N.K. Jain, Adhesive wear of
stir cast hypereutecticAl–Si–Mg alloy under reciprocating
slid in conditions, Wear 266 (2009) 1–5.
[3] J. Clarke, A. D. Sarkar, Wear characteristics of as-cast
binary aluminiumsilicon alloys, wear, 54 (1979) 7 –16.
[4] Toni Bogdan off and Jimmy Dahlstrom,The
influence of copper on an Al-Si-Mg alloy (A356) -
microstructure and mechanical properties, school of
engineering, Jonkoping University, june-2009, pp 10.
[5] K.B. Shah, Sandeep Kumar and D.K.Dwived, Aging
temperature and abrasive wear behavior of cast Al–(4%,
12%, 20%)Si–0.3% Mg alloys,Dec 2004.
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