Question

The creep mechanism observed at very low stresses with stress exponent $n=1$ is given by

• A. Harper-Dorn creep
• B. Nabarro-Herring creep
• C. Coble creep
• D. Power-law breakdown creep

Hint:

Low-stress creep with n≈1 indicates Harper–Dorn mechanism.

Answer 1

The Correct Option is A

Concept: Creep mechanisms depend on stress level, temperature, and diffusion processes. At very low stress, dislocation-controlled creep dominates.

Step 1: Stress exponent behavior.

• $n \approx 1$ → linear creep behavior
• indicates dislocation glide controlled mechanism

Step 2: Harper-Dorn creep.

• occurs at very low stresses
• dislocation glide dominates
• stress exponent $n \approx 1$ Final Answer: \[ \boxed{\text{Harper-Dorn creep}} \]