Q1: In age-hardenable alloys, maximum ductility is obtained

ANS:C - after optimum ageing.

In age-hardenable alloys, maximum ductility is typically obtained after the optimum aging process. During the aging process, the alloy undergoes precipitation hardening, where fine particles of a second phase precipitate within the matrix, strengthening the material. However, excessive aging (overaging) can lead to the coarsening of these precipitates, which may result in reduced ductility and toughness. Therefore, the optimum aging process achieves a balance between strengthening and maintaining ductility, resulting in a material with improved mechanical properties.