Effect of reinforcing shape on twinning in extruded magnesium matrix composites

The influence of the shape of the ceramic reinforcement, particles or whiskers, on the twinning mechanism in extruded magnesium matrix composites was investigated using in-situ synchrotron radiation diffraction and acoustic emission spectroscopy during compressive tests. The presence of the ceramic reinforcement hindered both twin nucleation and growth. Twinning in both composites is shifted towards higher applied stress, especially in that reinforced by whiskers. The load transfer capacity of SiC whiskers and the higher tensile residual stress developed in the matrix during the extrusion process in the AZ31-10%SiCw composite is superior to that of particles due to their higher aspect ratio.