采用铸造-倾析-铸造技术制备A390/A356铝合金功能梯度复合材料时过热和凝固层厚度对其界面接合的影响

摘要

The cast-decant-cast is a new method for the preparation of the functionally graded components that has been developed in recent years. The functionally graded cylindrical shape component with a radial gradient, e.g. the first alloy (A390) with high wear resistance on the surface of the piece and toughness and the second alloy (A356) of low machining costs in the core of the piece can be produced via this melt process. The effect of the second alloy superheat at temperatures of 750, 820 and 860 °C as well as the effect of the first alloy solidified layer at 25, 35 and 45 s decanting time on achieving the perfect interface between the two alloys was investigated. The characterization of the interface was carried out by optical microscopy and scanning electron microscopy, and its width was measured by the microhardness test. The results showed that the best interface was obtained at 860 °C and 35 s decanting time with a width of 500 µm. Also, the wear resistance test was performed to measure and compare the surface wear resistance to the core.%铸造-倾析-铸造技术是近年来发展起来的一种制备功能梯度材料的新方法。采用这种方法制备在径向具有梯度功能的圆柱形试样，其外表层为具有高耐磨性的 A390铝合金，芯部为具有较高韧性和加工性能的 A356铝合金。研究芯部熔体在不同过热温度(750，820和860°C)和表层在不同倾析时间(25，35和45 s)下的A390/A356合金界面接合情况。采用光学显微镜和扫描电镜对界面进行表征，对界面区的显微硬度进行测量。结果表明，在过热温度为860°C，倾析时间为35 s的条件下，可以获得一宽度约为500μm的接合良好的界面层。比较了试样表面层和芯部的耐磨性能。