Microstructure and Mechanical Properties of AZ81 Magnesium Alloy after Unequal Channel Angular Pressing

摘要

The microstructure and mechanical properties of AZ81 magnesium alloys after unequal channel angular pressing (UCAP) was investigated using self-made 90° die under different temperature. The results showed that under the same pressing speed, there was a better grain refinement and mechanical property improvement with the decreasing of pressing temperature, however, the tiny cracks on the surface of the processed samples increased. When squeezed at 250°C, the average grain was refined from the initial 150um to 10um. The tensile strength was changed to 350Mpa, and the elongation was of 10%. Tensile fractures presented the increment of dimples structure, which was the result of refined a-Mg matrix and intermetallic compound β-Mg_(17)Al_(12) phase by severe shear and plastic deformation at high temperature press.