Dynamic response and microstructure control of Al–Sc binary alloy under high-speed impact

It is concluded that the secondary Al3Sc particles play a predominant role on the high-speed impact process. The secondary Al3Sc particles have two effects of stabilizing the matrix structure and acting as source of dislocation. Because the capability of Al–Sc alloy to resist high-speed projectile impact is related to the microstructure, the development of Al–Sc alloy with a combination of fine-grain strengthening and precipitation strengthening is investigated. The results show that Sc additions greater than the eutectic composition (0.55 wt%) were found to produce a remarkable refinement in the grain size. Discontinuous precipitations, which are undesired, are prone to occur in the hypereutectic Al–Sc alloys. For the hypereutectic Al–Sc alloys, control of the aging temperature within a certain range can suppress the presence of discontinuous precipitation, thus the Al–Sc alloy can be strengthened by both the fine-grain strengthening and by continuous precipitation strengthening, which helps to improve the capability to resist high-speed impact.