Effect of thermal-cooling cycle treatment on thermal expansion behavior of particulate reinforced aluminum matrix composites

摘要

Two micron SiC particles with angular and spherical shape and the sub-micron Al2O3 particles with spherical shape were introduced to reinforce 6061 aluminium by squeeze casting technology.Microstructures and effect of thermal-cooling cycle treatment(TCCT) on the thermal expansion behaviors of three composites were investigated.The results show that the composites are free of porosity and SiC/Al2O3 particles are distributed uniformly.Inflections at about 300 °C are observed in coefficient of thermal expansion(CTE) versus temperature curves of two SiCp/Al composites,and this characteristic is not affected by TCCT.The TCCT has significant effect on thermal expansion behavior of SiCp/Al composites and CTE of them after 3 cycles is lower than that of 1 or 5 cycles.However,no inflection is observed in Al2O3p/Al composite,while TCCT has effect on CTE of Al2O3p/Al composite.These results should be due to different relaxation behavior of internal stress in three composites.