A novel process for grain refinement of Mg-RE alloys by low frequency electro-magnetic stirring assisted near-liquidus squeeze casting
A novel process for grain refinement of Mg-RE alloys by low frequency electro-magnetic stirring assisted near-liquidus squeeze casting
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DOI：
10.1016/j.jmatprotec.2022.117537
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发表时间：
2022-02-21
影响因子：
6.3
通讯作者：
Ding, Wenjiang
中科院分区：
文献类型：
--
作者：
Wang, Cunlong;Dong, Zeyi;Ding, Wenjiang
提出了一种低频电磁搅拌辅助近液相线挤压铸造（LFEMSNSC）制备稀土镁合金铸件的新方法。对比分析了常规重力铸造、挤压铸造和LFEMS-NSC对工业纯镁（CPMg）、包晶Mg-Zr合金和共晶Mg-Gd合金的晶粒细化效果。结果表明，LFEMS-NSC对CP-Mg和Mg-Gd合金具有有效的晶粒细化效果。将传统的重力铸造或挤压铸造工艺改为LFEMSNSC工艺，可使CP-Mg的晶粒形貌由粗大的柱状晶转变为细小的等轴晶。CP-Mg的平均晶粒尺寸从-10 mm细化到-232 μ m，细化效果与添加Mg-Zr中间合金相当。将LFEMS-NSC应用于Mg-Zr系和Mg-Gd系合金中也显示出明显的晶粒细化效果，且在溶质含量不同的情况下效果不同。LFEMS-NSC的晶粒细化机制主要是由于LFEMS对熔体的预处理和凝固过程中施加的压力提高了自由激冷晶体的存活率和非均匀形核率。
A novel method named low frequency electro-magnetic stirring assisted near-liquidus squeeze casting (LFEMSNSC) was developed for preparing Mg-RE alloy castings. The grain refining effect in commercially pure Mg (CPMg), peritectic Mg-Zr alloy and eutectic Mg-Gd alloy were comparatively analyzed among conventional gravity cast, squeeze cast and LFEMS-NSC. The results showed that the LFEMS-NSC exhibited effective grain refining efficiency in CP-Mg and Mg-Gd alloys. With changing conventional gravity casting or squeeze casting to LFEMSNSC, the grain morphologies of CP-Mg were transformed from coarse columnar into fine equiaxed grains. The average grain size of CP-Mg was refined from-10 mm to-232 mu m, where the grain refinement efficiency was comparable to that of adding Mg-Zr master alloy. The application of LFEMS-NSC to Mg-Zr and Mg-Gd alloy systems also show considerable grain refining effect, and it show different effectiveness when the solute content varies. The grain refinement mechanism of LFEMS-NSC is mainly because of the enhanced survival rate of free chill crystals and enhanced heterogeneous nucleation rate through melt pre-treatment by LFEMS and applied pressures during solidification.