(北京有色金属研究总院 有色金属材料制备加工国家重点实验室，北京 100088)
摘 要: 采用分级淬火试验方法，结合对合金峰时效态硬度、淬火态电导率的测试，拟合得到新型Al-7.5Zn-1.7Mg-1.4Cu-0.12Zr合金的温度—时间—性能(TTP)曲线，并与传统的7B04和7150合金进行比较。结果表明：新型合金的TTP曲线鼻温大约在290 ℃，其孕育期约为4.5 s，与同等条件下制备的7150合金(320 ℃，2.6 s)和7B04合金(335 ℃，0.1 s)相比，其TTP曲线的鼻温最低，对应的孕育期最长，反映出新型合金过饱和固溶体的稳定性最高，具有最低的淬火敏感性。进一步的TEM分析表明，随着鼻温附近保温处理时间的延长，合金内部的淬火脱溶析出现象不断加剧。淬火诱导脱溶η相优先在(亚)晶界上形核析出，在晶内依附于已存在的Al3Zr弥散相粒子形核析出；时效后，在这些粗大η相周围形成一定宽度的无沉淀析出带。合金的成分及组织形态影响和决定着合金的淬火敏感性；新型合金淬火可以适当降低冷却速度以减小残余应力。
关键字: Al-Zn-Cu-Mg合金；淬火敏感性；TTP曲线；脱溶析出
（State Key Laboratory of Nonferrous Metals and Processes, General Research Institute for Nonferrous Metals,
Beijing 100088, China）
Abstract:The quench sensitivity of an Al-7.5Zn-1.7Mg-1.4Cu-0.12Zr alloy was determined by temperature-time- property (TTP) curve by an interrupted quench method with the measurement of the hardness as aged and electrical conductivity as quenched compared with traditional 7B04 alloy and 7150 alloy. The results indicate that the nose temperature of TTP curve and the corresponding incubation period of the novel alloy, 7150 alloy and 7B04 alloy are about (290 ℃, 4.5 s), (320 ℃, 2.6 s) and (335 ℃, 0.1 s), respectively, the nose temperature of the alloy is the lowest among three alloys and the critical time at the nose temperature is the longest for the alloy, which is obvious that the supersaturated solid solution of the alloy is the most stable, exhibiting the alloy has the lowest quench sensitivity. Further, TEM analysis results show that, with the prolongation of keeping time at the nose temperature, the quench-induced precipitation phenomenon becomes obvious. The quench-induced η precipitates nucleate and precipitate at grain and sub-grain boundaries by preference, and the quench-induced precipitates appear to nucleate mostly on the pre-existing Al3Zr dispersoids. After aging treatment, these η precipitates were surrounded by a precipitate-free zone. The composition and microstructure morphology of alloy play an important role in the quench sensitivity of the alloy quenched. For the novel alloy, appropriately decreasing the cooling rate may be helpful to relieve the residual stresses.
Key words: Al-Zn-Cu-Mg alloy; quench sensitivity; TTP curve; precipitation
