Question

The microsegregation observed in casting is called

• A. Impurities
• B. Diffusion
• C. Dissolution
• D. Coring

Hint:

Coring is a common issue in cast alloys and can be reduced or eliminated by post-solidification heat treatment such as homogenization, which allows diffusion to even out composition gradients.

Answer 1

The Correct Option is D

Coring is a type of microsegregation observed in cast alloys, especially during solidification. It occurs when different regions within a grain solidify at different compositions due to non-uniform cooling. As the temperature drops, the alloying elements are distributed unevenly because diffusion is insufficient to homogenize the structure during the rapid solidification process. This leads to a composition gradient within the grains — richer in solute at the center and leaner at the periphery or vice versa. Coring weakens the mechanical properties and corrosion resistance of the cast material.