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运用光学金相显微镜、万能拉伸试验机、热场扫描电子显微镜、XRD衍射仪等设备和实验手段,研究了Y和Zr元素联合添加对A356铝合金微观组织和拉伸性能的影响。结果表明:Y和Zr是A356合金有效的变质剂,能使初生的α-Al晶粒变得圆整细小,二次枝晶间距减小,而且能使共晶硅由粗大的板条状转变为细小纤维状,提高合金强度和塑性,当Y和Zr的添加量均为0.2%时,合金抗拉强度和伸长率提升的效果最佳;当Zr的添加量提高至0.3%时,可能由于晶界上的偏析团聚未能消除,削弱了晶粒间的结合强度,导致合金抗拉强度和伸长率回落。
The effects of Y and Zr addition on the microstructure and tensile properties of A356 aluminum alloy were studied by means of optical microscope, universal tensile tester, thermal field scanning electron microscopy, XRD and other experimental equipments. The results show that Y and Zr are effective modifiers of A356 alloy, which can make the primary α-Al grains become round and small, the secondary dendrite spacing decreases, and the eutectic silicon can be transformed from coarse lath As the fine fiber, improve the alloy strength and plasticity, when Y and Zr are added 0.2%, the tensile strength and elongation of the alloy to enhance the best; when the amount of Zr added to 0.3%, may be due to The segregation on the grain boundaries can not be eliminated, weakening the bonding strength between the grains and causing the tensile strength and elongation of the alloy to drop.