Phase of different type of microstructure,Tin base babbit,self lubricating bearing material,Precipitation hardening Alloy

2. MATERIAL SCIENCE &
METALLURGY

3. STUDY OF MICROSTRUCTURE OF NON
FERROUS METALS AND ALLOYS
 Represented by
Nikhil Chavda (U14ME075)
Jay Lad (U14ME076)

5. Main non ferrous metals and alloys-

6. Index
 Brass Types
 α Brass
 Microstructure
 α- β Brass
 Microstructure :
 Tin Base Babbit
 Microstructure
 SELF LUBRICATING BEARING MATERIAL
 Microstructure
 PRECIPITATION HARDENING ALLOY
 Microstructure

7. BRASS(COPPER+ZINC)

8. α-Brass
 α-phase – FCC structure
 α-brass with less than 35% zinc
 It is very ductile
 Malleable, can be cold worked, It is used in pressing, forging, or similar
appplications
 They have fairly good corrosion resistance
 The α-brass are divided into two groups:
 Red α-brasses (5-20% zinc)
 Yellow α-brasses (20-30% zinc)

9. Continue..
 When the α brass is nearly cold worked (60% nearly) and heated to 300 °c
(Recrystallisation temperature) the grain growth of the material is
completed.
 Inside the grain some line appear- these lines area called annealed lines.
 Etching agent- Alcoholic ferrichloride
 Etching time – 10 to 12 sec
 Magification- 100X

10. Microstructure of α Brass

11. α grains increases with the zinc contents

12. α- β Brass
 Higher zinc contains (>39%)
 It contains both α and β phases at room tempture
 Two phase structure
 α phase : FCC structure
 β phase : BCC structure
 Due to the presence of the β phase, the alloy is harder and stronger and
therefore more brittle than α brass

13. Continue..
 Etching agent- Alcoholic ferrichloride
 Etching time – 10 to 15 sec
 Magnification- 200-300X
 It is generally hot worked
 As the contain of Zn increases β phase concentration increases..

14. Continue..
 This type brass is difficult to cold work, due to increasing amount of β phase.
 Decreased ductility due to the presence of the β phase(BCC)
 Increased strength and hardness due to increasing Zn content.

15. α phase
β phase

16. Tin Base Babbit
 Composition : 10-12% Antimony, 5-6% Copper, Remaining is Tin
 The structure of material has a comibation of soft material ( matrix )
arrangned in starset ( dentistic pattern)
 The centre set is made of neddle and starshaped in Cu3Sn
 Sn-Sb and Cu3Sn form the projection part of bearing material and support the
rotating journal

17. Continue..
 The solid solution ( matrix ) deform plastically during service and forms
channels through which lubricants are in constant circulation
 Etching agent- Diluted HNO3
 Etching time – 10 to 15 sec
 Magnification- 100-200X

18. Continue..
 Properties-
 Good ability to embed dirt
 Good conformability to journal
 Good corrosion resistance
 Very good seizure resistance, etc..

19. Microstructure tin base babbitt

20. Uses
For making heavy duty bearing to be used in …
Steam Turbine Turbo Pump Turbo Super charger

21. SELF LUBRICATING BEARING MATERIAL
 Composition - 89% Cu, 10% Tin, 1% Graphite ( Bronze with some amount of
graphite)
 The bearing of this material is made by power metallurgy method
 The structure is made up of solution of tin in copper (matrix) and graphite is
distrusted in the matrix
 Some small voids are also seen in structure

22. Continue..
 These voids are filled with oil before being filled to the machine
 Working
 When machine is running the oil comes out from the voids for lubricating
purpose and when machine stops oil slips in the voids and is not available
for lubrication. Under such condition, the graphite percent in the
material provide lubrication in the bearing

23. Continue..
 Etching agent- Diluted HNO3
 Etching time – 10 to 15 sec
 Magnification- 150-200X

24. Bearing bronze 200X etched

25. PRECIPITATION HARDENING ALLOY
 Precipitation hardening is commonly used to process Al alloys and other
nonferrous metals for commercial use. The example are Aluminum-copper,
copper-beryllium, copper-tin, magnesium-aluminum, and some ferrous alloys
 To obtain the structure , the alloy is heated to single phase material, held for
some time to allow the alloy to become homogenous rapidly.
 The fast cooling suppresses precipitation of Fe-Al. On heating this alloy to a
temperature of 100-150 °c the above intermediate compound precipitates
and material exhibits an increase in strength and hardness and decrease in
ductility

26. Continue..
 Etching agent- Diluted HNO3
 Etching time – 15 to 20 sec
 Magnification- 200-300X

27. PRECIPITATION HARDENING ALLOY