Effect of Y and Sm on microstructure and properties of AZ91D magnesium alloy

Abstract

The effects of solo rare earth Y and combined rare earth Y and Sm elements on the microstructure and mechanical properties of AZ91D magnesium alloy were studied by controlling variable method.The grain refinement mechanism of rare earth elements on AZ91D alloy was analyzed. The results show that the effect of combined addition of rare earth Y and Sm on AZ91D alloy is better than that of solo addition of rare earth Y significantly. More effective heterogeneous nucleation sites for α-Mg are achieved by adding Y and Sm to AZ91D alloy produced bulk phase Al2Y and acicular phase Al2Sm. When the addition content is 0.8% (mass fraction) Y and 1.0%Sm, the α-Mg grain size is the smallest and most uniform. The hardness, tensile strength and elongation of the alloy are 67.42HV, 153.37 MPa and 3.62% respectively, the mechanical properties of as-cast AZ91D alloy at room temperature are improved. However, the mechanical properties of the AZ91D alloy at room temperature decrease after exceeding this optimum addition.

Keywords

• mischmetal
• magnesium alloy
• grain refinement
• mechanical property