Al2O3-弥散强化铜合金的退火行为研究

摘要

采用原位反应合成技术制备了Cu-1.12wt％ Al2O3合金.通过力学性能测量、断口形貌观察及显微组织结构表征,系统研究了该合金的退火行为.结果表明:对冷拉拔变形量为50％的合金进行退火处理后,合金的硬度和强度均随着退火温度的提高呈缓慢下降趋势,合金韧性得到改善;合金表现为韧性断裂,且随着退火温度的升高,韧窝尺寸和深度增大,内部布满细小的纳米Al2O3颗粒;退火态合金位错密度低于冷拉拔态情形、中温退火(873 K)时合金组织以变形位错胞组织和位错墙为主,高温退火(1 223 K)后出现亚晶组织,偶可见亚晶合并、长大并发展成为原始再结晶核心的过程,但由于纳米Al2O3颗粒的钉扎位错作用和抑制再结晶效应,基体中仍未发现有明显的再结晶组织存在,合金展示出优异的抗高温软化性能.%Cu-1.12wt％ A12O3 alloy is fabricated by in-situ reactive synthetic technology,and its annealing behaviors are studied by means of mechanical property measurement,fracture morphology observation and microstructure representation,respectively.The results show that the Rockwell hardness and strength of Cu-1.12wt％ Al2O3 alloy with cold drawing deformation of 50％ slightly decrease with the increase in annealing temperature,and its toughness is also improved.The fracture mechanism of the alloy is a typical ductile fracture,the size and depth of dimple increase with the increase in annealing temperature,and many tiny alumina particles are bestrewn inside dimple.The dislocation density of annealed alloy is lower than that of cold-drawn alloy.The alloy microstructure is mainly composed of deformation dislocation cells and dislocation walls at intermediate annealing temperature (873 K).After high temperature annealing (1 223 K),the subgrain structure is formed,and the merging,growth and development of subgrains can be found to be a process of original recrystallization.As a result of the dislocation of fine alumina particles and grain boundary motion,no obvious recrystallized grains exist in the matrix.The Cu1.12 wt％ Al2O3 alloy has a high softening resistance at elevated temperature.