Effect of unequal channel angular pressing on microstructure and mechanical properties of as cast Mg-5.8Zn-1.2Y-0.7Zr alloy

摘要

The microstructure and mechanical properties of Mg-5.8Zn-1.2Y-0.7Zr alloys before and after unequal channel angular pressing (UCAP) have been investigated in detail using optical microscopy, scanning electron microscopy (SEM), X-ray diffraction, differential scanning calorimetry and mechanical property testing. The SEM and optical microscopy showed that the grain size was refined more at lower UCAP temperatures. When squeezed below 300°C, the average grain size was refined from the initial 110 μm to below 1.5 μm; the tensile strength increased to 390 MPa, and the elongation to break was over 13%. The high mechanical properties could be attributed to the reduced grain size and the strengthening effects of broken secondary phase particles and fine precipitates formed as a result of the severe shear and plastic deformation during pressing at high temperature.