应力时效对Al-Cu-Mg-Ag耐热铝合金组织与性能的影响  

Effects of External Stress During Aging on Microstructure and Properties of Al-Cu-Mg-Ag Alloy

作　　者：刘晓艳[1] 潘清林[1] 曹素芳[1] 陆智伦[1] 何运斌[1] 李文斌[1] 

机构地区：[1]中南大学材料科学与工程学院,长沙410083

出　　处：《航空材料学报》2010年第5期8-13,共6页Journal of Aeronautical Materials

基　　金：中南大学优秀博士学位论文扶植基金(2008yb012)

摘　　要：采用硬度测试、光学显微镜、透射电镜等研究了时效过程中外加应力对A l-Cu-Mg-Ag合金组织与性能的影响。结果表明,在应力时效和无应力时效的条件下,合金组织中均发生了完全再结晶,时效过程中施加外应力没有改变合金再结晶晶粒的形貌,但对析出相有较大影响。在应力时效条件下,合金中θ′相和Ω相均沿某一方向呈择优取向析出,即有应力位向效应产生。应力时效能够促进θ′相的析出,而抑制Ω相的析出,合金的峰值硬度也有所降低。这可能是由于在应力时效初期引入了大量的位错,为θ′相的异相形核提供了有利的位置,从而使与θ′相具有相同化学成分的Ω相的析出受到抑制。这一点从时效前预拉伸(变形量为6%)能够使θ′相数量增多而Ω相数量减少,且硬度略有降低得到验证。在应力时效过程中,位错的存在不利于溶质原子的扩散,阻碍了原子团簇的形成,从而延缓了合金中强化相的析出。The effects of external stress during aging on the microstructure and properties of Al-Cu-Mg-Ag alloy were studied by hardness test,optical microscopy（OM） and transmission electron microscopy（TEM）.The results show that completely recrystallization occurs in the alloys aged with and without stress.The morphology of the alloy is not changed when treated by stress-aged but the precipitations are changed greatly.Both θ′ phases and Ω phases precipitate to some preferred orientation,showing character of stress-orientation.The precipitation of θ′ phases is accelerated while that of Ω phases is restrained,and the hardness of the alloy is decreased to a small extent.This might be due to that the large amounts of dislocations during stress-aging provide sites facilitating heterogeneous nucleation of θ′ phases.Thereby,Ω precipitations with the same chemical constituents of θ′ phases are retained.This is verified by the phenomenon that the density of θ′phases is increased while that of Ω phases is decreased,and the hardness is reduced when Al-Cu-Mg-Ag alloy is pre-deformed 6% before aged.During the stress-aging,the existence of the dislocations disrupts the diffusion of the solution atoms,correspondingly distance the formation of the clusters and the co-clusters.As a result,the precipitations of the strength phases are delayed.

关 键 词：AL-CU-MG-AG 应力时效 位错 预变形 

分 类 号：TG146.21[一般工业技术—材料科学与工程]