Effect of grain size on the microstructure and mechanical properties of Mg-4Y-3Nd-0.5Zr alloy

Abstract Various grain sizes of an Mg-4Y-3Nd-0.5Zr alloy were obtained by changing the cooling rate in a casting with wall thickness from 10 to 70 mm, and the effect of grain size on the microstructure and mechanical properties was investigated. When the cooling rate increased from 23.6 to 240.2 K min−1, the grain size of as-cast specimens decreased from 115 to 42 μm, and the sizes of the eutectic phase morphology decreased. The ultimate tensile strength and tensile yield strength for heat-treated materials decreased 12 %–14 % due to the increase in grain size by decreasing the cooling rate. Meanwhile, both the ultimate tensile strength and yield strength showed a linear relationship with d−1/2 (d is the grain size).