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研究Sr对Mg-Al-Ca铸造合金微观组织演变的影响。研究发现,微量Sr会导致镁基体组织轻微粗化。当Sr含量从0.1%增加至0.5%时,镁基体的晶粒尺寸由83.9μm减小到65.8μm。添加0.1%-0.3%Sr对Al2Ca相有显著的变质细化作用,同时,使其形貌从条状转化为球状。Al2Ca的含量随着Sr元素的添加而有所增加。镁基体晶粒细化主要是由于Sr的添加增加了熔体的有效过冷度以及合金固/液界面前沿区域形成很强的成分过冷效应引起的。Sr对Al2Ca的变质作用主要归因于Sr在Al2Ca晶体上的吸附。当Sr含量增加至0.5%时,合金会出现过变质现象。
The effect of Sr on the microstructure evolution of Mg-Al-Ca alloy was investigated. The study found that trace amounts of Sr result in a slight coarsening of the magnesium matrix. When Sr content increased from 0.1% to 0.5%, the grain size of magnesium matrix decreased from 83.9μm to 65.8μm. Addition of 0.1% -0.3% Sr has significant metamorphism and refinement effect on Al2Ca phase, meanwhile, its morphology changes from strip to sphere. The content of Al2Ca increases with the addition of Sr. The grain refinement of the magnesium matrix is mainly due to the addition of Sr increasing the effective undercooling of the melt and the formation of a strong component undercooling effect in the frontal region of the alloy solid / liquid interface. The metamorphism of Sr on Al2Ca is mainly due to the adsorption of Sr on Al2Ca crystals. When the Sr content increased to 0.5%, the alloy will appear metamorphism.