The effects of yttrium on the microstructure and mechanical properties of AZ81 magnesium alloy have been investigated by alloy preparation

microstructure analysis and mechanical properties testing. The results indicate that 1%

2

% yttrium addition can obviously refine the structure of AZ81 magnesium alloy and restrain the creation of β（Mg17Al12） phase. At the same time

the needle-like and granular Al2Y phase distributed at grain boundary are observed. With the increase of yttrium content

the strength and elongation of the aged alloy at both room temperature and 150℃ is raised at first and then dropped. The maximum strength and elongation

277 MPa and 11% respectively

of the alloy at room temperature can be observed with 2% Y addition while they are 220 MPa and 12.4% respectively at 150 ℃with 1% Y addition. The strength at both room temperature and high temperature and plasticity of the alloy with Y addition can be improved

which is attributed to the solid solution strengthening

precipitation strengthening and fine-grained strengthening.