Hot Deformation Behaviors Of SiCp/AZ91 Magnesium Matrix Nanocomposite

In the present study,as-cast SiCp/AZ91 nanocomposite was fabricated successfully by semisolid stirring casting assisted ultrasonic vibration technology.Then the as-cast SiCp/AZ91 nanocomposites?CN?was subjected to multidirectional forging?MDF?to obtain fine-grain SiCp/AZ91 nanocomposites?FN?.The hot deformation mechanism of AZ91 alloy,CN and FN were investigated based on compression curves,as well as revealed influence on deformation behavior of matrix AZ91 alloy.The processing maps of three materials were calculated based on the processing map theory and the hot working domains were optimized according to microstructure and macro-structure.In addition,the effect of SiC nanoparticles,grain size as well as precipitated phase on the distribution of processing map was also investigated.After hot compression,the deformation bands in FN prepared by multidirectional forging under decreasing temperature condition were disappeared.Grain size increased with the rise of temperature and the decrease of strain rate.After peak stress,there was no obvious dynamic softening stage of FN compared with CN.The critical stress of FN was lower while the critical strain was higher than that of CN.The activation energy of FN was lower than that of CN.Under different deformation conditions,FN has different deformation mechanism.For AZ91 alloy,unstability occurred at high strain rate,the working domain was at 0.001-0.01s^-1?623-673 K.For CN,unstability region in high temperature area was decreased,while unstability area occurred in low temperature?573K?was bigger.Area of 623-673K?0.001-0.01s^-1 was the working domain.For FN,instability area mainly distributed in the high strain rate area,no instability occurred in the domain of 523K-673 K,the best working domain was 573K?0.001-0.01s^-1.Working domain of FN was significantly greater than of CN,and the working domain temperature?573K?of FN was lower than that of CN?623K-673K?.