Effect of SiC volume fraction on creep behavior of SiCp/2124Al metal matrix composite

The high temperature creep behavior of SiCp/2124Al metal matrix composites containing 10-30 vol percent of SiC particulate reinforcement was investigated to clarify the effect of the volume fraction of SiC particles on creep deformation. The SiCp/2124Al composites were fabricated by mixing 8-micron SiC particles and 20-micron 2124 Al powders, followed by hot pressing at 570 C and hot extrusion at 500 C with an extrusion ratio of 25:1. The high temperature creep behavior of SiCp/2124Al composites was investigated by constant stress creep tests at 300 C. The load transfer phenomena of a spherical particle in a metal matrix composite were analyzed based on the shear-lag model. The minimum creep rate of the SiCp/2124Al composite decreased with increasing volume fraction of SiC particles. The increase in the volume fraction of SiC particles reduces the effective stress for creep deformation of the Al matrix by the load transfer from the matrix to the SiC particles. The minimum creep rates of SiCp/2124Al composites with different volume fractions of SiC particles were found to be similar under an identical effective stress on the matrix, which is calculated by the modified shear-lag model. It is suggested that the role of SiC particles is to increase the creep resistance by reducing the effective stress acting on the matrix in metal matrix composites. (Author)