Spheroidization of primary Mg2Si in Al-20Mg2Si-4.5Cu alloy modified with Ca and Sb during T6 heat treatment process
Spheroidization of primary Mg2Si in Al-20Mg2Si-4.5Cu alloy modified with Ca and Sb during T6 heat treatment process
复制标题
Ca、Sb变质Al-20Mg2Si-4.5Cu合金中初生Mg2Si在T6热处理过程中的球化
DOI：
10.1016/j.msea.2016.12.080
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发表时间：
2017-02-08
期刊：
影响因子：
6.4
通讯作者：
Jiang, Qi-Chuan
中科院分区：
文献类型：
--
作者：
Yu, Hong-Chen;Wang, Hui-Yuan;Jiang, Qi-Chuan
研究了Al-20 Mg（2）Si-4.5Cu合金中初生Mg 2Si相的形貌演变规律。有趣的是，我们发现，热挤压和T6热处理的组合是有效的，在截断八面体的初级Mg 2Si转化为球形的改性合金。相比之下，未改性的合金中的初生Mg 2Si颗粒仍然保持枝晶。结果表明，铸态初生Mg 2Si颗粒截顶八面体的形成、热挤压破碎以及热处理过程中Si和/或Mg原子的固相扩散增强是初生Mg 2Si球化的主要原因。此外，细小（约10-20 μ m）球形初生Mg 2 Si的存在对合金的强化起着重要作用，即，抗拉强度（UTS）从未改性合金的227 MPa提高到改性合金的303 MPa。这是因为细小的球形初生Mg 2Si颗粒可以提供更高的断裂应力和基体/颗粒界面强度。本研究为在高Al含量的Mg 2Si合金中制备球形初生Mg 2Si提供了一种简单的方法，有利于设计新型轻质Al-Mg-Si合金，提高合金的力学性能。
The morphology evolution of primary Mg2Si particles in a Al-20Mg(2)Si-4.5Cu alloy both unmodified and modified with 0.5 wt% Ca-Sb prepared by hot-extrusion followed by T6 heat treatment was investigated in the present study. Interestingly, we found that the combination of hot-extrusion and T6 heat treatment was efficient in transforming truncated octahedral primary Mg2Si into sphere in the modified alloy. In contrast, the primary Mg2Si particles still kept dentritic in the unmodified alloy. It suggested that the formation of truncated octahedral primary Mg2Si particles in as-cast state, the fragmentation of particles by hot-extrusion and the enhanced solid-state diffusion of Si and/or Mg atoms during heat treatment were responsible for the spheroidization of primary Mg2Si. Moreover, the existence of fine (similar to 10-20 mu m) spherical primary Mg2Si played an important role in strengthening the alloy, i.e., the ultimate tensile strength (UTS) increased from similar to 227 MPa in the unmodified alloy to similar to 303 MPa in the modified one. It is because the fine spherical primary Mg2Si particles can provide a higher fracture stress and strength of the matrix/particle interface. Our study offered a simple methodology to prepare spherical primary Mg2Si in an Al-high Mg2Si alloy, which is beneficial to design novel light-weight Al-Mg-Si alloys with improved mechanical properties.