Enhanced strength-ductility synergy achieved through twin boundary pinning in a bake-hardened Mg–2Zn-0.5Ca alloy
Enhanced strength-ductility synergy achieved through twin boundary pinning in a bake-hardened Mg–2Zn-0.5Ca alloy
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DOI：
10.1016/j.msea.2021.142239
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发表时间：
2022-01
期刊：
影响因子：
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通讯作者：
Yi-Jia Li;Yuan Fang;Cheng Wang;Zhen-Ming Hua;Yipeng Gao;M. Zha;Huiyuan Wang
中科院分区：
文献类型：
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作者：
Yi-Jia Li;Yuan Fang;Cheng Wang;Zhen-Ming Hua;Yipeng Gao;M. Zha;Huiyuan Wang
烘烤硬化（BH）工艺是快速提高固溶处理后镁合金强度的有效途径，其主要原因是溶质偏析引起的GP区强化或位错钉扎。本文报道了BH在Mg-2 Zn-0.5Ca（wt.%）中的一种新的硬化机理。合金，即孪晶界钉扎，可以获得增强的强度-塑性协同效应，其流动应力为1.2200 MPa（从1.141 MPa增加），断裂伸长率为1.17%（从1.12%增加）。组织分析表明，Zn和Ca原子在10 1 <$2孪晶界处的共偏聚阻碍了孪晶界的迁移，有效地抑制了裂纹的扩展，从而提高了塑性。同时，孪晶界的钉扎作用与Zn和Ca原子在位错上的钉扎作用相结合，显著地提高了强度。这种孪晶界钉扎机制表明，BH技术可以普遍应用于开发具有增强的强度和塑性的高性能镁合金。
Bake-hardening (BH) processing is an efficient way to rapidly increase the strength of solution-treated Mg alloys, which is attributed to GP-zone strengthening or dislocation pinning caused by solute segregation. Here we report a new hardening mechanism of BH in Mg–2Zn-0.5 Ca (wt.%) alloy, ie, twin boundary pinning, which could obtain enhanced strength-ductility synergy, with a flow stress of∼ 200 MPa (increased from∼ 141 MPa) and an elongation to failure of∼ 17%(increased from∼ 12%). Microstructure analyses show that the co-segregation of Zn and Ca atoms at 10 1¯ 2 twin boundaries can impede twin boundary migration, which effectively suppresses crack propagation and therefore improves the ductility. Meanwhile, the twin boundary pinning obviously increases strength in conjunction with the pinning effects of co-segregated Zn and Ca atoms at dislocations. Such a twin boundary pinning mechanism suggests that BH technique can be generally applied to develop high-performance Mg alloys with enhanced strength and ductility.