(中南大学 材料科学与工程学院，长沙 410083)
摘 要: 通过分级淬火方法获得7050铝合金的时间—温度—性能(TTP)曲线。结果表明：合金TTP曲线的鼻尖温度为330 ℃，淬火敏感温度区间为240~420 ℃；等温保温时，过饱和固溶体分解析出第二相粒子，在330 ℃附近，第二相(主要为η平衡相)的析出速率达到最高；随着时间的延长，晶内η相数量增加、尺寸变大，时效后粒子周围出现无沉淀析出区，导致强化效果显著降低；晶界处η相粒子粗化，由不连续分布形貌转变为连续分布形貌，无沉淀析出带宽化；鼻尖温度的高相变驱动力和较快的扩散速率是η相析出和长大的主要原因，建议在淬火敏感区间应加快淬火冷却速率避免平衡相的析出，而高于淬火敏感区间温度时可适当降低冷却速率减小热应力的影响。
关键字: 7050铝合金；TTP曲线；淬火敏感性
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract: The time—temperature—property (TTP) curve of aluminum alloy 7050 was determined by an interrupted quench method. The results show that the quench sensitive temperature range of TTP curve of alloy is 240−420℃ with the nose temperature of 330 ℃. Microstructure observation indicates that the supersaturated solid solution decomposites and particles precipitate during quench process, the precipitation rate is the highest at about 330 ℃. A number of coarse equilibrium η particles precipitate at grain boundaries and in the grains during isothermal-holding at 330 ℃. Prolonging holding time leads to more and coarser η particles in the matrix, which results in loss of solutes and decrease of subsequent aging hardening effect, and more spaced η particles at the grain boundary that widen precipitation free zone. In the quench sensitive sector, primary precipitating reasons of η particles are severe phase transformation driving force and high diffusion rate of solute atoms. According the results, speeding up the cooling rate in the quench sensitive sector to reduce the precipitation of equilibrium phase is meaningful, and at higher temperature, decreasing the cooling rate is helpful to relieve the effect of thermal load.
Key words: 7050 aluminum alloy; TTP curve; quench sensitivity
