热处理工艺对触变成形AZ91D镁合金组织的影响

Effects of heat treatment processing on microstructures of thixoformed alloy AZ91D

对触变成形AZ91D镁合金在不同热处理条件下的时效组织进行了研究,结果表明:随着固溶温度的增加,第二相具有较大的时效析出速度,并且析出数量较多。经415℃、24 h固溶处理后的试样在时效处理过程中,第二相有两种析出方式:连续与不连续析出.在180℃没有连续析出,温度高于200℃后两种方式交替进行.时效处理温度越高,第二相析出的速度越快.同时也使得连续析出在很短时间内就开始发生,并且在晶粒内部与不连续析出互相交织在一起进行.

The aged microstructures of thixoformed alloy AZ91D were studied in different heat-treatment conditions. The results showed that faster precipitation rate of second phase happened and more quantity of precipitation was precipitated with increasing temperature. During aging treatment after solution treat- ment of the alloy at 415℃ for 24 h, there were two ways of precipitation of the second phase, namely continuous and discontinuous. The former did not happen at aging temperature 180℃, but both occurred alternatively when the aging temperature was above 200℃. The higher the aging temperature was, the quicker the second phase precipitated. Meanwhile, it made the continuous precipitation initiate very quickly and tangled up with the discontinuous one with in the interior of the grains.