双级时效对7475铝合金组织与性能的影响  

Effects of the two-step ageing on microstructure and properties of 7475 aluminum alloy

作　　者：段水亮[1] 刘志义[1] 段安静[1] 周杰[1] 

机构地区：[1]中南大学材料科学与工程学院,湖南长沙410083

出　　处：《金属热处理》2008年第8期112-115,共4页Heat Treatment of Metals

摘　　要：采用室温拉伸和电子显微分析方法(TEM)研究了7475铝合金在107℃和163℃的双级时效过程中微观组织变化和时效强化特点。结果表明,二级时效时间不变(163℃×30h),随一级时效时间延长,合金的抗拉强度增加,至6h后合金的抗拉强度减小,到10h后变化趋于平缓;一级时效时间不变(107℃×8h),随二级时效时间延长,时效初期合金的抗拉强度变化不大,时效至15h抗拉强度开始下降,时效至25h后渐趋平缓。透射电镜(TEM)观察发现,随一级时效保温时间延长,无沉淀析出带增宽;随二级时效保温时间延长,与T76相比,T73的微观组织中的GP区的数量减少,亚稳相η′和平衡相η数量增加。The microstructure and age-strengthening characteristics of 7475 aluminum alloy during a two-step ageing treatment at 107 ℃ and 163 ℃ were studied by tensile properties test and TEM observation. The results show that with fixed second step ageing time（ 163 ℃ × 30 h）, tensile strength value of this alloy enhances when the holding time of the first step ageing treatment increases until up to 6 h, at that time it decreases and becomes changeless after 10 h; with fixed first step ageing time（ 107 ℃ ×8 h）, tensile strength value of this alloy changes little until the holding time of the second step ageing treatment up to 15 h, at that time it decreases and becomes changeless after 22.5 h. TEM analysis re- veals that with increasing time of the first step ageing treatment, the precipitate free zones（PFZ） widen; with increasing time of the first step ageing treatment, the amount of GP zones decreases whereas those of metastable η′ phase and equi- librium η phase increases during T73 treatment,compared with those of T76 treatment.

关 键 词：7475铝合金 双级时效 透射电镜 抗拉强度 

分 类 号：TG156.92[金属学及工艺—热处理] TG146.2[金属学及工艺—金属学]