摘要
研究了Al—Cu—Mg—Ag—Zr合金高温短时拉伸和热暴露行为及其微观组织。高温拉伸试验结果表明，在150～250℃范围内，高温强度下降比较平缓，且250℃下的拉伸强度达到270MPa；在250～300℃范围内，高温强度迅速下降。热暴露试验结果表明，在相同时间的条件下，暴露温度从室温至150℃合金的强度和伸长率几乎没有变化，从200～300℃合金强度下降，但在200℃热暴露后的拉伸强度仍保持386MPa。透射电镜分析表明，合金欠时效状态由大量细小分布的Ω相及极少量的θ＇相组成，随着暴露温度的提高，Ω相长大并粗化，至250℃热暴露后Ω相大幅度减少，无析出带（PFZ）宽化。研究表明，短时高温拉伸条件下，Ω相在250℃下仍能保持稳定，而长时间（100h）热暴露时，Ω相只能在200℃下维持稳定。
Tensile property of an Al-Cu-Mg-Ag-Zr alloy at high temperature and effect of exposure at different temperatures on its mechanical property and corresponding microstructure were investigated. The results show that the strength of the alloy decreases slowly with increasing temperature below 250℃, and still reaches to 270MPa at 250℃, but descends quickly at the range of 250℃ to 300℃. The results of thermal exposure test show that no significant change of tensile property of the alloy thermally exposed at temperature lower than 150℃ is observed, however, the strength decreases rapidly for the alloy exposed at 200℃ to 250℃ for same time, while the tensile strength remains 386MPa after exposing at 200℃ for 100h. TEM observation suggests that the microstructure of the under-aged alloy consists of dispersed and uniformly distributed Ω phase and a few θ＇ phase in matrix. Ω phase particles grows up and coarsens with the increase of exposure temperature, and the amount of which greatly decreases and at the same time PFZ at grain boundary becomes widening. It is suggested that Ω phase remains stable for instantaneous tension at temperature below 250℃, whereas under the condition of thermal exposure for a long time, the temperature that Ω phase can keep stable is below 200℃ .
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2007年第6期50-53,共4页
Transactions of Materials and Heat Treatment
基金
国家"973"重点基础研究发展项目(2005CB623705-04)
