论文部分内容阅读
采用原位自生技术制备出不同Mg2Si含量的Mg2Si/Mg复合材料,利用光学显微镜观察其铸态组织,进一步研究了原位自生Mg2Si/Mg复合材料在不同温度和应力下的高温蠕变行为。结果表明,随着Si含量的增加,初生Mg2Si相从原来的块状向树枝状和花瓣状转变,分布在α-Mg和汉字状的共晶Mg2Si之间。原位自生Mg2Si/Mg复合材料的高温蠕变性能随着Mg2Si含量的增加而得到明显地提高,根据蠕变幂率方程,可求得材料的蠕变应力指数和表观激活能。该材料的蠕变表观应力指数均大于5,蠕变表观激活能大于纯Mg的蠕变激活能,且这2个参数在一定的条件下随着Mg2Si含量的增加而变大。该复合材料的蠕变机制主要是由位错攀移和第二相增强机制控制。
Mg2Si / Mg composites with different Mg2Si contents were prepared by in-situ technology. The as-cast microstructure of Mg2Si / Mg composites was observed by light microscopy. The creep behavior of Mg2Si / Mg composites at elevated temperatures under different temperatures and stresses was further studied. The results show that with the increase of Si content, the primary Mg2Si phase changes from original lumps to dendrites and petals, and distributes between α-Mg and Chinese-shaped eutectic Mg2Si. The in-situ creep property of Mg2Si / Mg composites increases obviously with the increase of Mg2Si content. According to the creep power rate equation, the creep stress exponent and apparent activation energy of the composites can be obtained. The apparent stress exponent of creep of the material is more than 5, and the apparent activation energy of creep is larger than the creep activation energy of pure Mg. The two parameters increase with the increase of Mg2Si content under certain conditions. The creep mechanism of the composites is mainly controlled by dislocation climbing and second-phase enhancement mechanism.