Effects of rare element and pressure on the microstructure and mechanical property of AZ91D alloy

•Microstructure of AZ91D alloy can be refined apparently by rare element Ce.•Pressurized solidification favors the flow and feeding capacity of residual liquid.•Micro-segregation and eutectic phase are reduced by strengthened flow behavior.•Shrinkage void is suppressed by the enhanced feeding capacity.•Both grain refinement and denser structure improve the tensile strength. Pressurized solidification in combination with grain refinement by rare element was performed for conventional AZ91D magnesium alloy. Both the resultant microstructure and mechanical properties of as-cast ingots were studied. After the addition of 0.75wt% Ce into AZ91D alloy, a comparable grain refinement can be achieved and an acicular phase Al11Ce3 is formed near the grain boundary. Affected by applying certain amount of pressure during solidification process, micro-segregation is weakened and the amount of shrinkage void in the microstructure is reduced due to the enhancement of flow and feeding capacity of residual liquid. Mechanical property evaluation reveals that the adoption of pressure with 0.2MPa during solidification generates significant improvement of tensile strength, which gives a promising method for the production of high performance lightweight magnesium alloy.