Study on Microstructure and Mechanical Properties of Mg-Zn-Y Alloy Prepared by Squeeze Casting
WU Jin-ke;HOU Hua;ZHAO Yu-hong;YANG Ling;CHENG Shu-jian;WANG Bing;School of Materials Science and Engineering, North University of China;
The effect of different applied pressures on microstructure and mechanical properties of squeeze cast Mg-Zn-Y alloy was investigated by optical microscopy(OM), scanning electron microscopy(SEM), X-ray diffraction(XRD), and tensile testing. The results show that microstructure of Mg_(93)Zn_6Y_1 alloy under different applied pressures consist of α-Mg and lamellar(α-Mg+I-Mg_3YZn_6) eutectic phase distributed between α-Mg dendrite. With the applied pressure increase, the α-Mg grain size obviously refines and the layer of eutectic organization become smaller, the eutectic changes from continuous mesh into the fracture network and dispersive distribution. The mechanical properties of the alloy increase gradually with increasing the applied pressure change from 0 to 150 MPa. When the applied pressure is 150 MPa, the ultimate tensile strength and elongation to failure are 193 MPa and 4.2%, respectively, which are 30.4% and 75.0% higher than the corresponding values of the samples prepared without applied pressure. The improvements of the tensile properties of alloy were ascribed to the grain boundary strengthening by grain refinement and strengthening by I-Mg_3YZn_6 phase. The fracture morphology of Mg-Zn-Y alloys shows the characteristic of quasi-cleavage fracture.