Remarkable age-hardening response and microstructural evolution of Mg-7Sn alloy
Remarkable age-hardening response and microstructural evolution of Mg-7Sn alloy
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DOI：
10.1016/j.jmrt.2023.03.087
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发表时间：
2023-03
期刊：
影响因子：
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通讯作者：
Lin Tong;Jing Jiang;Guang-li Bi;Zuocheng Xu;Yuandong Li;Tijun Chen;Xiaoru Zhang;W. Fu;D. Fang
中科院分区：
文献类型：
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作者：
Lin Tong;Jing Jiang;Guang-li Bi;Zuocheng Xu;Yuandong Li;Tijun Chen;Xiaoru Zhang;W. Fu;D. Fang
镁合金较差的时效硬化响应限制了镁合金的发展和应用。在220℃下进行40mpa的压应力时效处理，Mg - 7sn合金的时效硬化响应得到了显著改善，在应力时效过程中出现了由亚稳的β (Mg 3sn)相向β (Mg 2sn)相转变的过程。具有L1 2结构的β δ δ与Mg矩阵（1¯0）β′//(11¯0)α和[1¯1¯0]β′//（000 1¯¯α）具有取向关系。应力时效合金的析出顺序为：SSS（过饱和固溶体）→GP→β [m3sn]→β [m2sn]。与未施加应力的时效合金相比，应力时效合金具有较高的峰值硬度（~ 71 HV）和较短的时效时间（12 h）。有趣的是，在应力老化过程中，观察到一个71 HV，持续96 h的长时间老化平台。平台的形成与应力时效过程中微观组织演化过程中硬化与软化的平衡有关。应力时效是提高镁合金时效硬化性能的一种很有前途的热处理方法。
The poor age-hardening response of Mg alloys limited their development and applications. In this study, the age-hardening response of Mg–7Sn alloy has been improved significantly by a 40 MPa compressive stress aging at 220° C. Phase transition from metastable βˈ (Mg 3 Sn) phase to β (Mg 2 Sn) phase occurs during the stress aging. The βˈ with L1 2 structure has an orientation relationship with the Mg matrix of (1 1¯ 0) β'//(11 2¯ 0) α and [1¯ 1¯ 0] β'//⌈ 000 1¯⌉ α. The precipitated sequence in the stress-aged alloy is SSS (supersaturated solid solution)→ GP→ βˈ (Mg 3 Sn)→ β (Mg 2 Sn). The stress-aged alloy exhibits a high peak-aged hardness (∼ 71 HV) and short time to reach the peak hardness (12 h) as compared with the aged alloy without the stress. Interestingly, a long-time aging platform with 71 HV for 96 h is observed during stress aging. The formation of the platform is related to a balance of hardening and softening arisen from microstructure evolution during stress aging. The stress aging provides a promising heat treatment way to improve aging hardening response of Mg alloys.