Physical Metallurgy - Study Mode

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[#86] In a dilute solid solution of nickel and carbon in y-iron.

(A) D c > D NI

(B) D c < D NI

(C) D c > D Fe

(D) D c = D NI

Correct Answer

(D) D c = D NI

[#87] Match the heat treatment for an eutectoid steel shown in the TTT diagram below (as P, Q, R and S) with the resulting microstructure listed below: 1. Fine pearlite 2. martensite 3. Bainite 4. Coarse pearlite

(A) P-1, Q-2, R-4, S-3

(B) P-4, Q-1, R-3, S-2

(C) P-2, Q-1, R-3, S-4

(D) P-1, Q-4, R-3. S-2

Correct Answer

(B) P-4, Q-1, R-3, S-2

[#88] Match the phenomena listed in Group I with the possible mechanisms in Group II . Group I Group II P. Fatigue 1. Grain boundary sliding Q. Creep 2. Slip band extrusion and intrusion R. Strain hardening 3. Cottrell atmosphere S. Yield point phenomenon 4. Dislocation interaction

(A) P-2, Q-3, R-4, S-1

(B) P-2, Q-4, R-3, S-1

(C) P-2, Q-1, R-4, S-3

(D) P-1, Q-2, R-4, S-3

Correct Answer

(C) P-2, Q-1, R-4, S-3

[#89] An Al 4.5 mass% Cu alloy solutionising at 500°C, quenched to room temperature and aged at 200°C for 2 hrs is found to exhibit an increase in hardness. Theprimary mechanism contributing to increased hardness is

(A) martensitic transformation due to quenching

(B) solid solution strengthening

(C) precipitation hardening

(D) point defect strengthening

Correct Answer

(C) precipitation hardening

[#90] The low angle grain boundary occurs when the orientation difference between the adjacent grains is of the order of

(A) 100°

(B) 10°

(C) 1

(D) none of these

Correct Answer

(C) 1