27vol％－SiC_w／6061Al复合材料170℃时效的双硬度峰现象

THE PHENOMENON OF DOUBLE AGING PEAKS IN 27% vol-SiC_w/6061Al COMPOSITE AT 170℃

本文采用挤压铸造法制备２７％ｖｏｌ－ＳｉＣ_ｗ／６０６１Ａｌ复合材料，并对该种复合材料在１７０℃时效的动力学过程进行了研究，结果发现在时效动力学曲线上出现了双硬度峰现象。ＤＳＣ分析结果表明复合材料中β＇相及β相的析出温度与６０６１合金相对比分别降低５６℃和７６℃，由此讨论了ＳｉＣ晶须加入对复合材料脱溶过程的影响，并认为双时效峰现象与材料中的析出由Ｇ．Ｐ．区向β＇相的转化有关，通过ＴＥＭ观察，发现复合材料时效过程中析出相形貌的变化，在组织结构上提供了确凿的证据。

The 27% vol-SiCw/6061Al composite was fabricated by squeeze casting method .The aging dynamic process of the 27% vol-SiCw/6061Al composite was studied at 170℃, and double aging peaks were found in the aging dynamic curves of the composite, The results of DSC analysis showed that the precipitation temperature of β' and βphase in the composite decreased by 56℃ and 76℃, respectively as compared with that in the 6061Al alloy , from which the effects of the SiC whiskers on the precipitation processes of the composite were discussed. It is concluded that the double aging peaks resulted from the transformation of the precipitation from G. P. zones to β' phase, and this conclusion was further proved by TEM observation of the morphology of the precipitations in the 27% vol-SiC_w/6061Al composite.