please answer A and D

(a) Selection of the right material to build a component is based on what property? (6) We pass an aluminum alloy plate through a series of rolling mills, trying to reduce its thickness and produce foil. After passing through the second or third mill the metal hardens and becomes brittle. Why did that happen? (c) We anneal the rolled aluminum plate at 300 C. Recrystallization and for longer holding times grain growth will occur. What is the driving energy for these mechanisms; which is desirable, and which is undesirable and why? (d) Explain why a given alloy has a higher yield strength, if fine-grained rather than coarse grained. (20)