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在Mg-Al合金熔体中添加MnCO_3细化剂,研究了MnCO_3对铸造Mg-Al系合金晶粒尺寸的影响,并运用“边-边匹配”模型结合热力学与微观组织的分析,探讨了其细化机制。结果表明,MnCO_3对铸造Mg-Al合金晶粒有明显的细化作用,且对AZ31合金的细化效果最好。通过“边-边匹配”模型计算及热力学分析可知,经MnCO_3变质后,镁液中有可能生成Al_4C_3、τ-AlMn化合物,这些化合物与Mg有多对晶体学位向关系,可以作为α-Mg的有效形核质点。
The effects of MnCO_3 on the grain size of Mg-Al based alloy were studied by adding MnCO_3 refiner to Mg-Al alloy melt. The “edge-edge matching” model was combined with the analysis of thermodynamics and microstructure Its refinement mechanism. The results show that MnCO_3 has obvious thinning effect on the cast Mg-Al alloy grains, and the refining effect of AZ31 alloy is the best. Through the calculation of “edge-edge matching” model and thermodynamic analysis, we know that Mn_ (3) and Ta_AlMn compounds are likely to be formed in the magnesium solution after MnCO_3 metamorphism. These compounds have many pairs of crystal orientation relationship with Mg, Effective nucleation of Mg particles.