Young's modulus of elasticity of a material is the slope of the initial linear portion of the stress-strain curve. It decreases ap-preciablyby

ANS:B - heat treatment

The Young's modulus of elasticity (also known as modulus of elasticity or elastic modulus) represents the stiffness of a material and is typically measured from the initial linear portion of the stress-strain curve. The factors that affect the Young's modulus include:

1. Alloying Additions: The addition of certain elements to a material can alter its microstructure and the interactions between its atoms or molecules, thus affecting its elastic properties. Depending on the specific alloying elements and their concentrations, the Young's modulus may increase, decrease, or remain relatively unchanged.
2. Heat Treatment: Heat treatment processes such as annealing, quenching, and tempering can modify the internal structure of a material, influencing its mechanical properties including the Young's modulus. For example, heat treatment can induce changes in grain size, crystal structure, and dislocation density, which in turn affect the material's elasticity.
3. Cold Work (Strain Hardening): Cold working, also known as strain hardening or cold deformation, involves plastic deformation of a material at temperatures below its recrystallization temperature. This process can lead to an increase in dislocation density and changes in the material's crystal structure, resulting in an increase in strength but potentially a decrease in the Young's modulus.
4. Increasing Temperature: Increasing temperature can cause changes in the atomic or molecular structure of a material, affecting its elasticity. For many materials, an increase in temperature can lead to thermal expansion, which may alter the material's stiffness and hence its Young's modulus. Additionally, at elevated temperatures, materials may undergo phase transitions or other thermal effects that influence their mechanical properties.

In summary, the Young's modulus of a material can be influenced by alloying additions, heat treatment, cold work, and increasing temperature. The specific effect of each factor depends on the material composition, processing history, and operating conditions.