Effects of SiC orientations and particle sizes on the low cycle fatigue properties of SiCp/A356 composite

•Spray deposition was applied to prepare 4.5 μm and 20 μm SiCp/A356.•Longitudinal sample has a superior fatigue property to transverse sample.•Stress amplitude order: 20 μm SiCp/A356 > matrix alloy > 4.5 μm SiCp/A356.•SiC decohesion or broken causes a decline of fatigue life at SiCp/A356.•Failure mechanisms of SiCp/A356 are dependent on SiC sizes and orientations. Herein, effects of SiC orientations and sizes on fatigue behaviors of SiCp/A356 composites are investigated. Results reveal longitudinal (LT) samples possess superior fatigue properties compared to transverse (TR) samples. Adding 4.5 μm SiC, deformation mechanisms transfer from dislocation pile-ups along Si to along both SiC and Si, contributing to SiC decohesion and degradation of fatigue resistances. Adding 20 μm SiC, SiC decohesion prevails at TR sample since angle θ between SiC orientation and loading direction locates 45°-135°, while broken SiC particles are predominant at LT sample as θ 135°. These further decline their fatigue life.