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Nanoscale precipitations in deformed dilute alloying Mg-Zn-Gd alloy
Materials & Design ( IF 8.4 ) Pub Date : 2020-11-01 , DOI: 10.1016/j.matdes.2020.109122
Hongwei Miao , Hua Huang , Shihao Fan , Jinyun Tan , Zhongchang Wang , Wenjiang Ding , Guangyin Yuan

Abstract Nanoscale precipitations in deformed dilute alloying Mg-Zn-RE alloys usually play critical positive roles in mechanical properties, while characterizing them still poses a significant challenge due to their small size and low volume fraction. Here, we conduct a systematic structural analysis of the nanoscale secondary phase particles, including W phase, a small amount of I phase and a handful of Mg3Gd phase, in hot deformed dilute alloying Mg-Zn-Gd alloy by combining atomic-resolution transmission electron microscopy with first-principles calculations. The investigation of atomic structure of nanoscale W phase reveals that the stoichiometric composition of W phase is determined by the quantity of Mg atoms which are replaced by Zn at certain positions. Furthermore, nanoscale W phase, I phase and Mg3Gd phase particles could exhibit certain orientation relationships and coherent or semi-coherent interface with Mg matrix, which contributes to atomic bonding at their interfaces. We also identify a phase transition from Mg3Gd phase to W phase, which is further supported by first-principles calculations showing that Mg3Zn3Gd2 phase is energetically more favorable than Mg3Gd phase. The phase transition between W phase and I phase could also take place during hot deformation and is reversible by absorbing or releasing Zn atoms at the interfacial region.

中文翻译:

变形稀合金化 Mg-Zn-Gd 合金中的纳米级析出

摘要 变形稀合金化 Mg-Zn-RE 合金中的纳米级析出物通常对机械性能起着至关重要的积极作用,但由于它们的小尺寸和低体积分数,表征它们仍然构成重大挑战。在这里,我们通过结合原子分辨率透射电子技术对热变形稀合金化 Mg-Zn-Gd 合金中的纳米级二次相颗粒进行了系统的结构分析,包括 W 相、少量 I 相和少量 Mg3Gd 相。显微镜与第一性原理计算。对纳米级 W 相原子结构的研究表明,W 相的化学计量组成是由在某些位置被 Zn 取代的 Mg 原子的数量决定的。此外,纳米级 W 相,I 相和 Mg3Gd 相颗粒与 Mg 基体可以表现出一定的取向关系和相干或半相干的界面,这有助于它们界面上的原子键合。我们还确定了从 Mg3Gd 相到 W 相的相变,这得到了第一性原理计算的进一步支持,该计算表明 Mg3Zn3Gd2 相在能量上比 Mg3Gd 相更有利。W 相和 I 相之间的相变也可以在热变形过程中发生,并且通过在界面区域吸收或释放 Zn 原子是可逆的。第一性原理计算进一步支持了这一点,表明 Mg3Zn3Gd2 相在能量上比 Mg3Gd 相更有利。W 相和 I 相之间的相变也可以在热变形过程中发生,并且通过在界面区域吸收或释放 Zn 原子是可逆的。第一性原理计算进一步支持了这一点,表明 Mg3Zn3Gd2 相在能量上比 Mg3Gd 相更有利。W 相和 I 相之间的相变也可以在热变形过程中发生,并且通过在界面区域吸收或释放 Zn 原子是可逆的。
更新日期:2020-11-01
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