Effects of Mg and Si in Al Matrix on Dimensional Stability of SiCp/Al Composites during Temperature Change

摘要

In this paper, based on the parameters of cumulative residual strain (CRS), the effects of different contents of Mg and Si elements in Al matrix on the dimensional stability of SiCp/Al composites was investigated and analyzed in the temperature interval of 25～400°C. Results show that，with the increasing of Si content in Al matrix, the CRS fluctuates only in a small range of strain, adding Si in Al matrix is beneficial to the dimensional stability of the composites, which can be improved through pre-thermal cycling; with the increasing of Mg content in Al matrix, the absolute value of negative CRS of the composites becomes smaller at the beginning and then turns positive, adding Mg in Al matrix causes the composites expand after several thermal cycling, it is not good to the dimensional stability of the composites and is quite impossible to be improved by pre-thermal cycling. Besides, the CRS in thermal cycling is mainly caused by the plastic relaxation, which results in the irreversible dimensional variation of about 10~(-5)～10~(-4).