Tensile behavior of Mg-Zn-Ca-Zr alloy forged in semi-solid state

The Mg-6.0%Zn-2.0%Ca-1.5%Zr (mass%) alloy is suitable for a prematerial all oy in semi-solid forging because of its fine spherical structure and igniti on-proof property. The tensile behavior dependent on the microstructural fa ctors, such as size and form factor of primary or phase and the distance of crack propagation in the semi-solid forged alloys with solid fractions of 65 and 70% is clarified. The tensile properties are compared to those of th e squeeze cast alloy as well. The size of primary or phase increases with a n increase in holding time. In contrast, the size of remelted and resolidif ied alpha phase remains unchanged. The tensile strength and 0.2% proof stre ss of the semi-solid forged alloys decrease as the size of the ripened prim ary or phase increases, indicating the dependence of strength on the size o f the ripened primary Lu phase. The elongation increases with an increase i n holding time. The result is interpreted by the facts that the distance of crack propagation increases due to the increasing size of the ripened prim ary alpha phase and that the form factor of the ripened primary alpha phase is lowered by tensile deformation with an increasing holding time. The rem elted and resolidified alpha phase has no effect on the tensile properties with an increase in holding time. The elongation of semi-solid forged alloy is approximately two times larger than that of the squeeze cast alloy.