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%SiC composite is superior to that of particles due to their higher aspect ratio.Magnesium Elektron is kindly acknowledged for supplying the AZ31 cast alloy. BESSY (Berlin, Germany) is kindly acknowledged for beam time on the beamline EDDI. We kindly acknowledge the support of the EU during the measurements at BESSY. We should like to acknowledge financial support of the Spanish Ministry of Economy and Competitiveness under project number MAT2012-34135. The K.M. are grateful for the financial support of the Czech Science Foundation under the contract 14-36566G.Peer Reviewe