Micromechanical properties and deformation damage behaviors of SiCp/Al composites using cryogenic indentation technique

SiC particles-reinforced aluminum matrix (SiCp/Al) composites have been widely used in aerospace science and engineering fields. Nevertheless, the evolution of mechanical properties and deformation behaviors at cryogenic temperatures remains unclear, which still limits their manufacturing process and applications. In this paper, indentation responses of SiCp/Al composites were systematically investigated using instrumented grid indentation at room and cryogenic temperatures. According to the image processing technology of microstructure and statistical analysis of multi-modal Gaussian distribution functions, a novel method is developed that accounts for both particle properties and grid indentation spacing. Additionally, this work reveals a remarkable effect of the cryogenic environment on micromechanical properties and deformation behaviors during indentation. The results indicate that the elastic moduli increase by 12.67% for SiC particles and 55.22% for the 6092 aluminum matrix with the temperature decreasing from room temperature to -150°C. The composites exhibit remarkable weakness in wear resistance below -100°C, which is mainly attributed to the coupling effect of thermal contraction mismatch (∼ 0.00245) and indentation-induced reaction stress for SiCp/Al composites. This work may provide more in-depth thoughts on the evolution of micromechanical properties at cryogenic temperatures.