Microstructure evolution and properties of Mg-3Sn-1Mn (wt%) alloy strip processed by semisolid rheo-rolling

The high cooling rate caused by the sloping plate and stirring action caused by the vibration and metal flow lead to a high nucleation rate as well as two primary grain growth patterns, direct globular growth as well as dendrite growth and subsequent breakage, which causes the formation of fine spherical or rosette primary grains. The change of the primary grain shape is not obvious in the roll gap. However, solid fraction increases from the entrance to the exit of the roll gap. The spherical or rosette grains were remained eventually. When the casting temperature is 670 °C, and the vibrating amplitude is 1.5 mm, the strip with a cross section of 4 mm×160 mm was produced. Homogeneous microstructure was obtained. Mechanical properties of the present product were higher than that of Mg-3Sn-1Mn (wt%) alloy casting with the addition of 0.87 wt% Ce.