EFFECT OF DOUBLE-AGING ON MECHANICAL-PROPERTIES OF MG-6ZN REINFORCED WITH SIC PARTICULATES

Double-age hardening characteristics of a Mg-6% Zn alloy reinforced with 20 vol % SiC particulates (SiC(p)) were examined. Tensile tests were conducted using specimens with two different double-ageing treatments. Examination of the fracture surface using scanning electron microscopy and energy dispersive analysis of X-rays, and study of the precipitation process using transmission electron microscopy were undertaken to supplement the mechanical test data. The results show pre-ageing below the Guinier-Preston zone solvus strengthens the matrix through refinement of precipitates, and in turn leads to an increase in strength and decrease in composite ductility. In addition, as the yield and ultimate tensile strength of the composite increase, involvement of SiC(p) in the fracture process increases.