含Ag的Al-Cu-Mg基合金的断续时效特征

摘要

采用维氏硬度、拉伸力学性能测试、扫描电镜和透射电子显微镜分析手段,研究了断续时效对含Ag的Al-Cu-Mg基合金的组织和性能的影响。结果表明：185℃高温欠时效Al-Cu-Mg-Ag合金在低温进行二次时效时,会发生二次析出现象,合金塑性显著提高。随着185℃欠时效时间的延长,合金二次时效初始硬度升高,峰值时间缩短,峰值硬度增量降低。二次时效温度为65℃时,合金中主要强化相为G.P.区和少量的Ω相,其峰值强度硬度低于T6态,提高二次时效温度至150℃,合金主要强化相为Ω相和少量的G.P.区,其峰值强度硬度略高于T6态。%The effects of interrupted ageing on microstructure and mechanical properties of Al-Cu-Mg alloy with trace Ag were investigated by means of Vickers hardness test（HV）,tensile test,scanning electron microscopy（SEM） and transmission electron microscopy（TEM）.The results show that if Al-Cu-Mg-Ag alloy was underaged at 185℃,and then hold at a lower temperature,the alloy will undergo so-called ＇secondary precipitation＇.And the plasticity of the alloy will be improved.If the time of underageing at 185℃ is elongated,the initial hardness of secondary ageing increases,and both the time of peak hardness and the net hardness increment are reduced.When the secondary aging temperature is 65℃,the dominant hardening precipitates are G.P.zones.The mechanical properties,hardness and strength are lower than those of the peak-aged alloy of T6 temper.But if the secondary aging temperature is elevated to 150℃,the dominant hardening precipitates will be changed to Ω phases,and the mechanical properties of alloy will also be improved.