Effect of homogenizing treatment on microstructure and mechanical properties of Mg-Nd-Zn-Zr alloy

doi:10.13251/j.issn.0254-6051.2020.05.028

Abstract

Abstract: Effect of homogenizing treatment on the microstructures and mechanical properties of Mg-2.3Nd-0.5Zn-0.5Zr alloy was investigated by optical microscopy(OM), differential thermal analysis(DTA), X-ray diffractometry(XRD), scanning electron microscopy(SEM) and tensile test. The results show that the as-cast alloy is composed mainly of α-Mg, strip-like Mg₁₂Nd phase and petaloid Zn-Zr phase. After homogenizing treatment, the strip-like Mg₁₂Nd phase gradually dissolves into the matrix, while there are also partial petaloid Zn-Zr phase within the grains. The best homogenizing treatment for the alloy is 505 ℃×6 h, which leads the secondary phase at grain boundary to dissolve into the matrix so that the elongation of the alloy increases by 100%, and the fracture mode of the alloy changes from the brittle cleavage fracture in as-cast state to the ductile transgranular fracture. However, such a process causes weakening of both the secondary phase strengthening and the grain refinement strengthening so that offsets the solid solution strengthening, which result in that the tensile strength and yield strength of the alloy increase slightly.

Key words: Mg-Nd-Zn-Zr alloy, homogenizing, microstructure, mechanical properties

CLC Number:

TG146.2

Su Zaijun, Zhu Wen, Yang Shuzhong, Luo Linshan. Effect of homogenizing treatment on microstructure and mechanical properties of Mg-Nd-Zn-Zr alloy[J]. Heat Treatment of Metals, 2020, 45(5): 147-151.

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