Microstructure evolution of SiCw/AZ91 magnesium matrix composite during high temperature compression
(1.黑龙江省哈尔滨市哈尔滨工业大学材料科学与工程学院2.School of Materials and Engineering, Harbin Institute of Technology, Harbin 150001, China3.School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China)
Abstract: The compressive behavior of the squeeze cast SiCw/AZ91 composite was investigated at 400℃ and strain rate of 0.01s-1 by Gleeble-1500 thermal mechanical simulator. The microstructure evolution of the composite during compression was observed by scanning electron microscope(SEM) and transmission electron microscope (TEM). The results indicate that the microstructure evolutions involve the movement of SiC whiskers and the changes of the matrix. The rotation and the broken of SiC whiskers tend to be obvious with the increasing strain. At the initial stage of compression (ε=1%), high density of dislocations was observed in the matrix. And at further strain (ε=10%), a number of twins are formed in the matrix. In this case, some twins intercept with each other and are broken with the increasing strain, and dynamic recrystallization (DRX) grains are nucleated at twin boundaries and twin intersections.
Key words: magnesium matrix composite； high temperature compression； whisker； twin