Effects of Compound Adding Ce, Sr and La on Microstructures and Mechanical Properties of Alloy AZ91

The effect of Ce, Sr and La on the microstructur es and mechanical properties of the alloy AZ91 was investigated. The results show that Ce, Sr and La can refine the as-cast microstructure of AZ91 alloy remarkably. The morphology of β-Mg17Al12 phase transforms from a net shape to a bulk and granular shape, and β-Mg17Al12 phase distributes in the matrix of the alloy AZ91 uniformly. In addition, some bacilliform or acicular Al4 Ce and Al4 La phases appear in the alloy AZ91. The microstructure is optimal when adding 0.5wt.% Ce, 0.2wt.% Sr and 0.3wt.% La simultaneously, and the tensile strength and elongation of the alloy AZ91 achieve 270 MPa and 7.75% respectively.