Funct. Mater. 2019; 26 (4): 759-766.

doi:https://doi.org/10.15407/fm26.04.759

Studying the effect of equal channel angular extrusion on microstructure and properties of Mg2Si vehicle magnesium alloy

F.Shen

School of Automobile Engineering, Chongqing Three Gorges Vocational College, Wanzhou, Chongqing, China

Abstract: 

The thermal stability of the Mg-Zn-Si magnesium alloy is investigated. The Mg-Zn-Si magnesium alloy was deformed using the ECAP process at a deformation temperature of 573 K under angular extrusion. Using the methods of optical microscopy, X-ray diffractometry, electron microscopy, and transmission electron microscopy, the characteristics of the microstructure of a deformed magnesium alloy Mg-Zn-Si are studied. The mechanical properties of the deformed alloy were tensile tested at room temperature, and creep was studied at high temperature. The results show that the α-Mg matrix, the MgZn phase and the Mg2Si phase are purified and evenly distributed with an increase in the extrusion pass number. Refining of the α-Mg matrix is generated after 1-pass of extrusion. The size of α-Mg decreased to 5-10 μm after 4-pass extrusion, and the grain size was uniform. The dendrite of the Mg2Si phase was granular in the initial position after 2-pass extrusion, and the dispersed distribution of the Mg2Si phase was generated after 6-pass extrusion and 8-pass extrusion. The yield strength and tensile strength of the alloy were increased by 120 % after 4-pass extrusion, and the elongation of the alloy increased by 353 %. After 8-pass extrusion, the tensile strength and elongation of the alloy did not change much compared to 4-pass extrusion, but the yield strength was further increased by 19 %. As the extrusion pass number increases, the creep resistance at high temperature increases, and the constant creep rate decreases five times after 8 passes. The mechanism of grinding of the Mg2Si phase consists in shear mechanical fragmentation.

Keywords: 
equal channel angular extrusion (ECAP), Mg<sub>2</sub>Si Vehicle Magnesium Alloy, mechanical properties, microstructure, Mg<sub>2</sub>Si phase.
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