Compressional Deformation On The Microstructure And Mechanical Properties Of Mg-zn-y Alloys

In this paper, several as-cast Mg-Zn-Y bulk alloys, which consisted of a coarse eutectic I-phase in the a-Mg matrix, were fabricated by using the conventional casting method of the design of composition: Mg₉₈Zn_1.7Y_0.3, Mg₉₅Zn_4.3Y_0.7, Mg₉₃Zn₆Y_1.0. Mg-Zn-Y alloys have been extruded. Scanning Electron microscope,transmission electron microscope, X-rayer were used to analyse alloy's micro-structure, the electron extend machine and micro-hardness tester were used to test the mechnical properties.In order to fill the request of the intensity , toughness, wearablity,mould steel 3Cr2W8V had been used to be the material .Mg-Zn-Y alloys have been extruded at different temperature and extrusion ratio.The result showed that when the temperature was473K,because of the less of the slippage system,Mg alloys had been destroyed;with when the temperature was 623K,the surface temperature have been advanced by the extrusion heat,which can made the surface framewoke brittle,so the crack come into being.The microculture can be finned by the extrusion,and the I-phase which limitrophed in the boundary of the crystal have been destroyed and distributed into the basement of the Mg alloys.The results also showed that,the temperature and extrusion ratio had some effecfson the microculture and mechanical properties of the alloys. When the extrusion ration increased and the extrusion temperature reduced, the microstructure became finer and the distribution of I-phase became more homogeneous,and the grain sizedecreased from 40-60μm to 8-15μm.. The mechanical properties were improved by hot extrusion processing, and the strength, hardness and elongation were increased with the increasing of extrusion ration.When the extrusion tempexatue become 575K,the size of the crystal framework have grew up, the second phase became less,the distribution became more homogeneous,the micro-hardness decreased smaller and the intensity increased. With the increaseing of the content of Y,I-phase became more,a lot of fibre framework occurred, the micro-hardness decreased smaller and the...