Grain growth of an aluminium [formula omitted] PMMC during solution heat treatment

Abstract

Particulate reinforced metal-matrix composites (PMMC's), particularly those based on aluminum matrices, are candidate materials for both aerospace and automotive applications. Although processing routes have been developed and the mechanical properties of these materials examined, their microstructural behavior during deformation at both room and elevated temperatures and following subsequent annealing has not been widely studied. One aspect of importance is the effect of the reinforcement particles on grain growth following recrystallization. This is especially relevant in composites based upon age-hardenable aluminum alloys, where solution heat treatment following working is often desirable, so that a maximum amount of solute can be retained in solid solution prior to subsequent age hardening. Recrystallization may occur rapidly during such heat treatments and undesirable coarse grain structures may develop readily. It is clearly important to control of microstructure to maintain desirable mechanical properties. This paper presents data on the grain growth at 500 C of a PMMC consisting of a 2xxx series alloy matrix reinforced with alumina particles. This behavior is compared with the grain growth behavior of the unreinforced aluminium matrix. The size distribution of the matrix grains in the composite is compared with the particulate distribution. The grain growth data obtained are compared withmore » theoretical models of grain growth.« less