Effects of Ga on microstructure and mechanical properties of HSRRed Mg–Zn–Zr alloys

Abstract

Effects of Ga alloying on microstructure and mechanical properties of Mg–6Zn–0.6Zr alloys and the mechanism have been explored. In addition to being solidly soluble in the α-Mg matrix, Ga also reacts with Zn and Zr to produce GaZr2 and Ga-riched Mg7Zn3 particles. The formation of these intermetallics consumes solute atoms in the α-Mg matrix which weakens its beneficial effect on the dynamic recrystallisation behaviour of the alloys. The Ga addition reduces both strength and ductility of the Mg–6Zn–0.6Zr alloy sheets produced by high strain rate rolling processing due to the bigger grain size and the decreasing degree of dynamic recrystallisation. The decline in ductility can also be ascribed to the existence of the coarse Ga-riched Mg7Zn3 particles.