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采用金相显微镜、X-射线衍射分析仪和电子探针研究了Cr含量(质量分数分别为0、0.2%、0.4%、0.6%和0.8%)对含1.2%Fe的A356合金的铸态显微组织的影响。结果表明,当合金中未加入Cr时,显微组织中存在着大量的粗大针状铁相;当合金中加入0.2%Cr时,合金中粗大的针状Fe相开始出现断裂分叉现象,同时针状Fe相的长度变短,而Fe相形貌并没有明显的改变;当Cr含量增加至0.4%时,针状Fe相逐渐转变为细小汉字状;当Cr含量超过0.6%时,Fe相则变成粗大的鱼骨状甚至块状。因此,要获得较佳的铸态显微组织,Cr的加入量约为0.4%~0.6%。
The as-cast microstructure of A356 alloy with 1.2% Fe was studied by metallographic microscope, X-ray diffraction and electron probe. The results showed that the content of Cr (mass fraction 0, 0.2%, 0.4%, 0.6% and 0.8% Impact of micro-organization. The results show that there is a large amount of coarse acicular iron phase in the microstructure when no Cr is added into the alloy. When 0.2% Cr is added into the alloy, the coarse acicular Fe phase begins to fracture and bifurcate, meanwhile, The length of acicular Fe phase became shorter and the morphology of Fe phase did not change obviously. When the content of Cr increased to 0.4%, the acicular Fe phase gradually turned into small Chinese character. When the content of Cr exceeded 0.6% It becomes coarse fish bones or even lumps. Therefore, to obtain better cast microstructure, the amount of Cr added is about 0.4% ~ 0.6%.