热暴露对Al-Cu-Li合金的组织及性能影响
Effect of thermal exposure on the microstructure and properties of an Al-Cu-Li alloy
吴名冬 1肖代红 1黄兰萍 1刘文胜1
作者信息
- 1. 中南大学轻质高强结构材料重点实验室,湖南 长沙 410083
- 折叠
摘要
Al-Cu-Li合金作为航空航天工业中一种前景广阔的结构材料,其热稳定性在实际应用中发挥着重要作用.本研究对T85态的Al-Cu-Li合金在一系列温度(100～300℃)下进行了500 h的暴露处理,并通过维氏硬度、电导率和拉伸测试对其性能进行了评估.结合扫描电子显微镜(SEM)和透射电子显微镜(TEM)分析了不同热暴露温度下的微观结构演变.结果表明,热暴温度低于150℃时,合金具有良好的热稳定性,这与T1(Al2CuLi)相的直径和数密度不断增加相关.当热暴露温度介于150～200℃时,T1相逐渐被粗大的θ'-Al2Cu和S-Al2CuMg取代;同时,断续的晶界析出物(GBPs)和宽的无析出区(PFZs)利于沿晶断裂,使合金呈现出沿晶-穿晶混合断裂,导致硬度和强度的降低和延伸率的增加.热暴露温度高于 250℃时,T1相全部溶解,形成了粗大的 T2(Al6Cu(Li,Mg)3)和C相,从而导致合金的强度下降,但延伸率和电导率却表现出相反的趋势.
Abstract
As a promising structural material in the aerospace industry,the long-term thermal stability of Al-Cu-Li alloys plays an important role in practical applications.In this study,the T85-treated Al-Cu-Li alloy subjected to thermal exposure at a range of temperatures(100～300℃)for 500 h,is evalu-ated by Vickers hardness,electrical conductivity and tensile tests.The microstructure evolution at dif-ferent heat exposure temperatures is analyzed by a combination of scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The results show that excellent thermal stabil-ity in strength is obtained below 150℃,which can be related to the increasing diameter and number density of the T1(Al2CuLi)phase.In the 150～200℃ window,the T1 phase is gradually replaced by coarse θ'-Al2Cu and S-Al2CuMg with increasing temperature.Simultaneously,discontinuous grain boundary precipitates(GBPs)and soft precipitation-free zones(PFZs)lead to intergranular ductile fracture dominance,exhibiting mixed ductile and brittle fracture.At temperatures above 250℃,the T1 phase is completely dissolved and coarse T2(Al6Cu(Li,Mg)3)and C phases are formed.This leads to a dramatic decrease in the strength,while elongation and conductivity show an opposite trend.
关键词
Al-Cu-Li合金/热暴露/力学性能/显微组织Key words
Al-Cu-Li alloy/thermal exposure/mechanical properties/microstructure引用本文复制引用
基金项目
重点实验室装备预研基金资助项目(6142912180105)
重点实验室装备预研基金资助项目(41422060204)
出版年
2024
NETL
NSTL
维普
万方数据