Effect of heat treatment on microstructure and properties of as-extruded Mg-6Gd-5Y-1Zn alloy

doi:10.13251/j.issn.0254-6051.2020.08.031

Abstract

Abstract: Microstructure and mechanical properties of as-extruded Mg-6Gd-5Y-1Zn (mass fraction, %) alloy after solid solution and aging treatment were investigated. The results show that the as-extruded alloy is composed of α-Mg matrix, strip shaped 18R-LPSO phase arranged parallel to extrusion direction, Mg₂₄(GdYZn)₅phase and fine lamellar 14H-LPSO phase. Solid solution (T4) treatment of the as-extruded alloy at high temperature results in the dissolution of 18R-LPSO phase into the matrix and the lengthening and coarsening of the 14H-LPSO phase. A large number of β′ precipitates exist in the microstructure of the T6 treated specimens. The T6 treated specimen shows the best tensile properties at room temperature with tensile strength of 406 MPa, yield strength of 272 MPa and elongation of 6.1%. T5 treatment also results in the β′ precipitation but its volume fraction, as well as the volume fraction of the 14H-LPSO phase are much lower than that of the T6 treated specimens.

Key words: magnesium alloy, long period stacking ordered structure (LPSO), precipitated phase, hot extrusion, solid solution, aging

CLC Number:

TG146.22

Xu Hengyuan, Zhen Rui, Mao Zhongfeng, Wu Zhen, Dai Shengpeng. Effect of heat treatment on microstructure and properties of as-extruded Mg-6Gd-5Y-1Zn alloy[J]. Heat Treatment of Metals, 2020, 45(8): 161-165.

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