Deformation behavior and microstructure evolution of AZ31B composites containing multiscale distribution during room temperature tensile

摘要

The tensile strength of the AZ31B alloy with multiscale distribution has been greatly improved when compared with conventional Mg alloys. Its properties have also been determined to be sensitive to the interaction between multiscale SiC and dislocations. This work studies how multiscale SiC affects this material's properties, as well as how it modifies the deformation/fracture behavior of matrix, through transmission electron microscope (TEM) examination of the elongated samples. When the strain increases, it is easy to form stress concentration in the zone around micron SiC, thus causing the activation of dislocation. The presence of relatively more number of small sized (evenly distributed submicron or nano) SiC seen in the space left between micron SiC would actively pin the dislocation and act as dislocation movement obstacle, resulting in the increase of dislocation density around SiC. Moreover, the addition of micron or submicron SiC is responsible for the increase of deformation stability. Although the strain localization around micron SiC could promote the nucleation of cracks, the dispersed nano or submicron SiC could delay and suppress the crack propagation. Moreover, compared with micron SiC, the nano SiC/Mg interface exhibits stronger bonding, so that the crack propagation is delayed due to the addition of nano SiC, and the ductility of material with multiscale distribution is reserved. (C) 2019 Elsevier B.V. All rights reserved.