The microstructure and the associated hardness,strength and electrical conductivity of a new Al-Zn-Mg-Cu alloy during one-step ageing treatment were systematically studied.The results show that the electrical conductivity of the alloy increased continuously with increasing ageing temperature and ageing time.At the early stage of ageing,the hardness and strength of the alloy increased rapidly and then reached the peak value.When aged at 120 ℃,the hardness and strength maintained at high level for a long time after the peak value.The main precipitations are GPⅠ zones,GPⅡ zones and metastable η' phase.GPⅠ and GPⅡ zones arefound in the alloy after ageing for 24 h at 120 ℃,which indicates that some stable GP zones can exist through the ageing process.When aged at 160 ℃,the hardness and strength decreased rapidly after the peak value.The precipitation process is significantlypromoted compared with that aged at 120 ℃.Both GPⅠ zones and GPⅡ zones disappeared after ageing for 1 h at 160 ℃.The main precipitates are η' phase when aged at 160 ℃ for 1 h.The main precipitates are η phase when the ageing time prolongs to 24 h.%对一种新型高强Al-Zn-Mg-Cu合金在单级时效过程中的硬度、强度、电导率变化及相应的析出行为进行系统的研究.结果表明,电导率随着时效温度的升高和时效时间的延长而不断增高.在时效开始阶段,硬度和强度随着时效的进行迅速升高并达到峰值.在120℃时效时,硬度和强度到达峰值后保持稳定,主要的析出相是GPⅠ区、GPⅡ区和η'相.在120℃长时间(直至24 h)时效后,GPⅠ区和GPⅡ区仍能稳定存在.在160℃时效时,硬度和强度到达峰值后迅速下降.与120℃时效相比,在160℃时效时,析出过程更快.在160℃时效1h后,未观察到GPⅠ区及GPⅡ区的存在,主要的析出相为η'相.在160℃时效24 h后,主要的析出相为η相.
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