Question

Identify the structure-sensitive property:

• A. Density
• B. Yield stress
• C. Specific heat
• D. Coefficient of thermal expansion

Hint:

As a rule of thumb, mechanical properties related to deformation and fracture (like yield strength, tensile strength, hardness, fatigue life, fracture toughness) are structure-sensitive. Physical properties (like density, melting point, specific heat, thermal expansion) are generally structure-insensitive.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Material properties can be classified into two categories:

• Structure-insensitive properties: These properties are primarily determined by the nature of the atoms and the strength of their interatomic bonds. They are not significantly affected by changes in the microstructure (e.g., grain size, defects).

• Structure-sensitive properties: These properties are highly dependent on the material's microstructure, including features like grain size, dislocations, precipitates, and other defects.
The question asks to identify the structure-sensitive property from the given list.

Step 2: Detailed Explanation:
Let's analyze each option:

• (A) Density: Density depends on the atomic mass of the constituent atoms and how closely they are packed in the crystal lattice. It is largely insensitive to microstructure.

• (B) Yield stress: Yield stress is the stress at which a material begins to deform plastically. Plastic deformation occurs by the movement of dislocations. The ease or difficulty of dislocation motion is strongly influenced by microstructural features like grain boundaries, solute atoms, and precipitates, which act as obstacles. Therefore, yield stress is a classic example of a structure-sensitive property.

• (C) Specific heat: This is the amount of heat required to raise the temperature of a unit mass of a substance by one degree. It is an intrinsic thermodynamic property determined by atomic vibrations and is structure-insensitive.

• (D) Coefficient of thermal expansion: This describes how the size of an object changes with a change in temperature. It is related to the asymmetry of the interatomic potential energy curve and is also structure-insensitive.

Step 3: Final Answer:
Among the given options, yield stress is the property that is highly dependent on the material's microstructure, making it a structure-sensitive property.