高硅镁合金的制备工艺及显微组织分析

汽车发动机传动系统可采用的镁合金有AZ91D ,AM 6 0B合金[1,2 ] 。但是这些合金的抗蠕变能力较低 ,使镁合金构件与与之连接的构件间易产生旷动 ,最终导致失效。目前所开展的耐热镁合金的研究 ,其目标是在不大幅度提高成本的基础上 ,提高镁合金在 15 0～ 2 5 0℃下的高温强度和蠕变性能 ,并且具有良好的压铸性能和耐蚀性[3～ 5] 。本实验研究了高硅镁合金的熔炼制备工艺 ,分析了合金的显微组织结构。1　试验过程镁合金熔炼前首先按照实验计划进行合金的配料计算 ,然后准备炉料及所需的非金属辅助材料。将坩埚预热至暗红色 (4 0 0～ 4 5 0…

Preparation Process and Microstructure of High-Silicon Magnesium Alloy

The preparation technique for a high silicon magnesium alloy ASE640 was explored. Different addition forms of silicon element to magnesium melt were compared and the master alloy method was selected. In addition, microstructure and phase structure of this alloy were investigated with optical microscope, scan electronic microscope and X ray diffraction meter. The dissolution rate of Si in magnesium melt was discussed. It shows that the smaller the primary silicon strips in the master alloy are, the higher the dissolution rate and the less dissolution time are. The experimental results show that in as cast ASE640 alloy a lot of Mg 2Si intermetallic compound particles are found and they present the shape of Chinese characters. However, the mechanical properties at room temperature and creep properties at elevated temperature are decreased for the coarse Mg 2Si grains. The Mg 2Si grains can be refined by hot extrusion and dispersed uniformly in the matrix, which may efficiently improve the mechanical properties of the alloy.