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. (C) 2013 Elsevier B.V. All rights reserved.