21. Match the names listed in Group I with the reactions listed in Group II.
Group I
Group II
P. Eutectic
1. γ + β ⟶ α
Q. Peritectic
2. L ⟶ α + β
R. Peritectoid
3. L1 ⟶ L2 + α
S. Monotectic
4. L + β ⟶ α
| Group I | Group II |
| P. Eutectic | 1. γ + β ⟶ α |
| Q. Peritectic | 2. L ⟶ α + β |
| R. Peritectoid | 3. L1 ⟶ L2 + α |
| S. Monotectic | 4. L + β ⟶ α |
22. Pb-Sn is an example
23. Atomic packing factor of BCC crystal structure is
24. Identify the attributes associated with dispersion hardened alloys.
P. Dispersoids do no dissolve in the matrix even at high temperature.
Q. Dispersoids are coherent with the matrix.
R. Dispersoids impart creep resistance to the alloy.
S. Dispersoids improve the corrosion resistance of the alloy.
P. Dispersoids do no dissolve in the matrix even at high temperature.
Q. Dispersoids are coherent with the matrix.
R. Dispersoids impart creep resistance to the alloy.
S. Dispersoids improve the corrosion resistance of the alloy.
25. Internal cracks in drawn bars are due to
26. Von Mises criterion for plastic yielding of a ductile metal predicts that the yield stress in uniaxial tension is related to that in pure torsion as
27. During decarburising of a plane carbon steel, the thickness of ferrite layer growth is proportional to
28. A steel specimen containing 0.2 wt.% C is carburized in an atmosphere that maintains a carbon content of 1.2 wt.% C at the surface of the specimen.
Given:
For carbon diffusion in austenite: D0 = 2.0 × 10-5 m2/s
Activation energy for diffusion, Q = 142 kj/mol
y
erf(y)
0.85
0.7707
0.90
0.7970
0.95
0.8209
What is the depth (in (μm) from the surface of the specimen at which a composition of 0.4wt.% C is obtained after carburizing at 870°C for 10 h?
Given:
For carbon diffusion in austenite: D0 = 2.0 × 10-5 m2/s
Activation energy for diffusion, Q = 142 kj/mol
| y | erf(y) |
| 0.85 | 0.7707 |
| 0.90 | 0.7970 |
| 0.95 | 0.8209 |
29. The plane strain fracture toughness (KIC) and yield strength of a material are $$100\,M{N^{ - \frac{3}{2}}}m$$ and 500 MN-2m respectively. The minimum plate thickness to determine KIC is . . . . . . . . cm.
30. Gold has surface free energy of 1.5 J.m-2 and grain boundary energy of 0.365 J.m-2.
The groove angle that forms where a grain boundary intersects the free surface in a well annealed sample is
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