Deformation rate effect on the microstructure and mechanical properties of Al-SiCp composites consolidated by hot extrusion

In the present study, the effect of the ram speed was investigated on the final microstructure and mechanical properties of the Al-SiCp composites through the hot extrusion process. The extrusion process was conducted at 550 degrees C by applying different ram speeds in the range of 0.2-4 mm s(-1). Optical image microscopy (OIM) results showed that by applying the higher value of ram speed, a microstructure can be obtained including oriented SiC particles in the Al matrix. Finite element analysis (FEA) was also utilized to examine the velocity components values at different ram speeds during the extrusion process. The differences in spacing between particle chains at the edge and center of the extruded samples were minimum at ram speed 2 mm s(-1). The mechanical properties of the final products were examined by the means of uni-axial tensile and Vickers micro-hardness tests. The tensile test results showed that the highest values of ultimate tensile and yield stresses were obtained at the ram speed 2 mm s(-1). There is a good agreement between the change in the microstructure and the hardness values gradient through the longitudinal cross-section. (c) 2012 Elsevier B.V. All rights reserved.