Thermal Stress Analysis Of Particle Reinforced Aluminum Matrix During Stabilized Treatment

The Al2O3P/2024Al composites and SiCP/2024Al composites used in the model were fabricated by squeeze casting method. The temperature changing with the time during quenching and different thermal-cooling cycling treatment was measured by temperature meter. The microstructure was observed by scan electron microscopy (SEM) and transmission electron microscopy (TEM). The micro-yield strength after different stabilized treatment and dimensional stability in thermal cycling conditions of SiCP/2024Al composites were measured by tension test and dilatometer. The planimetric model of composites for thermal stress analysis was established by Marc finite element software. Thermal stress of the composites during different heat treatments was analyzed by Marc software. The effect of volume fraction, particle shape and stabilized treatment technology on the thermal residual stress in the composites was investigated. The thermal residual stress was the important factor of the composites dimension stability. Thermal stress of the composites during stabilized treatment was numerically simulated by finite element method. The result showed that during heat treatment the microstress caused by the thermal mismatch between particle and the matrix. When the microstress was higher than the yield strength of the matrix the matrix would produce plastic deformation. The thermal residual stress of low volume fraction Al2O3P/2024Al composites was found more even. With the volume increased, part of thermal residual stress in composites began to lap each other. The thermal stress field nearing the particle-matrix interface distributed evenly due to the global particles. The thermal stress field nearing the particle-matrix interface distributed unevenly due to the angle particles. There were thermal stress and plastic strain concentration near the particle corner obviously. The thermal residual stress of composites was decreased and the thermal stress concentration near the particle corner was also decreased evidently after thermal-cooling cycling treatment. The lower the lower limit temperature was the smaller thermal residual stress was. The first cycling played the leading role.The micro-yield strength and dimensional stability in thermal-cycling conditions of SiCP/2024Al composite were affected greatly by different dimensional stabilizing techniques. In thermal-cooling cycling, with difference in temperature increasing, the long range residual stress relieved easily, the dimensional stability in thermal-cycling conditions became better, which was accordance with the simulated result. The best technology improving the dimensional stability of SiCP/2024Al composites under no load condition was the technique of 160℃~-196℃ cycling. Under load condition micro-yield strength of SiCP/2024Al composites decreased with difference in temperature increasing.