Precipitate evolution of as-cast Mg-9Gd-2Y-0.5Zn-0.5Zr alloy containing LPSO, β′′, β′ and γ'' phases during isothermal aging at 200

• Published in: Journal of alloys and compounds Vol. 917; p. 165476
• Main Authors: Zhao, Xin, Yang, Zhong, Meng, Xiangsong, Dong, Xiongbo, Li, Jianping, Liang, Minxian
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 05.10.2022; Elsevier BV
• Subjects: Age hardening; Age-hardening curve; Aging (artificial); Chemical precipitation; Evolution; Gamma-double prime phase (crystals); Heat resistant alloys; High temperature; In situ heating scanning; Mechanical properties; Mg-Gd-Y-Zn-Zr alloy; Phase transformation; Phases; Precipitates; Phase transformation; Age-hardening curve; In situ heating scanning; Mg-Gd-Y-Zn-Zr alloy
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2022.165476

In this work, the evolution process, crystallinity, microstructure and morphology of Mg-9Gd-2Y-0.5Zn-0.5Zr (wt%) alloy precipitates were analyzed during isothermal aging at 200 ℃. During the early stages of aging, the precipitate phase distributed in the matrix is mainly the β′′ phase, which exhibits a hexagonal D019 structure. In the peak-aged stage, the γ′′ phase, LPSO phase, and β′ of the precipitates coexist in the matrix. The synergism between the three types of phases is significant with respect to the improved age-hardening. We propose that the optimized mechanical properties of the alloy originate from the co-precipitation of the LPSO, β′, and γ'' phases. Furthermore, it is an important way to improve the performance of the alloy at high temperatures. •The change process of different types of precipitates in GW92ZK alloy.•The relationship between them is established by calculating the energy of precipitated phase and the mismatch degree.•By establishing a schematic diagram, the orientation relationship between precipitated phase and matrix is shown.