喷射沉积SiC_p/Al-20Si-4.5Cu梯度复合材料的优化热处理工艺

Optimum Heat Treatment Processes of SiC_p/Al-20Si-4.5Cu Gradient Composites Prepared by Spray Deposition

采用喷射沉积技术制备了SiCp/Al-20Si-4.5Cu梯度复合材料,并对其进行致密化和不同温度、时间的固溶、时效热处理,通过对比硬度得出优化的热处理工艺参数;然后对热处理前后的试样进行拉伸试验,并观察拉伸断口形貌。结果表明:该复合材料优化的固溶温度为485℃,固溶时间为1.5h,时效温度为175℃,时效时间为7h;SiC颗粒含量的梯度变化导致复合材料时效速度呈梯度变化;高SiC含量的表层峰值时效后的抗拉强度最高,为432MPa,其伸长率为5.8%,此时沿SiC颗粒含量梯度降低方向上的复合材料则处于欠时效状态,塑性较好;梯度复合材料中高SiC含量表层的脆性断裂特征明显,沿梯度方向上随SiC含量的降低,复合材料拉伸断口上的韧窝增多,韧性断裂趋势增强。

A SiCp/A1-20Si-4. 5Cu gradient composite was prepared by spray deposition and densification technologies, and different solid solution and aging heat treatments were completed. The optimum beat treatment process was obtained by hardness comparing, and then the samples before and after heat treatment were tested by tensile testing and tensile fracture morphology was observed. The results show-that the optimum solution temperature of the composite was 485℃, the solution time was 1.5 h, the aging temperature was 175℃ and the aging time was 7 h. The gradient change of aging rate for the composite was resulted from that of SiC content. The surface layer with the high SiC content exhibited the highest strength of 432 MPa and the elongation of 5.8% in the peak-aged state, and the composite along SiC content gradient lower direction was in under-aged state and exhibited better plasticity. The surface layer with high SiC content exhibited obvious brittle fracture feature, while the layer with the lower SiC content along the gradient direction demonstrated more dimples, enhanced the trend of ductile fracture characteristic.