过剩硅含量对Mg2 Si/Al复合材料组织和耐磨性的影响

采用重力铸造法制备不同过剩硅含量的原位Mg_2Si/Al复合材料,研究过剩硅含量对Mg_2Si/Al复合材料组织和耐磨性的影响.结果表明:随着过剩硅含量、磷加入量的增加,初生Mg_2Si的体积分数增加,尺寸却减小;初生硅的体积分数随过剩硅含量的增加而增加;当过剩硅的含量增加到16%时,初生硅的平均尺寸没有发生明显变化,规则生长的α-Al树枝晶不断破裂,变得圆整;初生硅依附或包围初生Mg_2Si生长.当初生Mg_2Si和初生硅同时存在时,磷对初生Mg_2Si的变质效果优于其对初生硅的变质效果.干滑动试验发现,在恒定的载荷、滑动速率以及磨损距离下,随着过剩硅含量的增加,Mg_2Si/Al复合材料的磨损失重逐渐减小.

Effects of Extra Si Content on Microstructure and Wear Resistance of Mg2 Si/Al Composites

In-situ Mg2 Si/Al composites with different extra Si contents were successfully synthesized by gravity casting technique. The effects of extra Si content on microstructures and wear resistance of Mg2 Si/Al composites were studied. The results show that:with increasing of content of extra Si and P,the number of primary Mg2Si increased and the size became smaller, at the same time, the number of primary silicon increased. When the content of extra Si was 16%,the average size of primary silicon remained unchanged. The morphology of α-Al changed from dendrite to broken dendrite and became gradually round. Some primary Mg2 Si particles were clung or wrapped up by primary Si. In addition, the wear test results showed that the wear volume decreases with increasing the fractions of extra Si at a constant sliding distance,sliding speed and applied load.