热处理对Ti-2.5Cu合金组织和性能的影响

Effect of heat treatment on microstructures and properties of Ti-2.5Cu alloy

i- 2 .5Cu合金是含有 (w (B) ) 2 .5 %Cuβ共析型元素的近α型二元合金 ,具有可与纯钛相媲美的成型性和可焊性 ,有一定的热强性 ,使用温度可达到 35 0℃ .通过对Ti- 2 .5Cu合金板材进行不同退火和固溶时效制度处理后 ,测试其室温拉伸性能和HV值 ,并利用光学显微镜和透射电镜观察其组织形貌 ,对该合金热处理制度与组织、性能关系进行了深入、系统地研究 .结果表明 ,Ti - 2 .5Cu合金最佳退火温度为(790± 10 )℃ .为了缩短时效时间 ,可采用双重时效制度 ,一次时效 40 0℃ ,8h ,空冷 ,二次时效 475℃ ,8h ,达到最佳的强化效果 ,此时Ti2 Cu粒子析出并长大到最佳尺寸 10

Ti-2.5Cu alloy is a binary near α titanium alloy containing 2.5wt% Cu, which is a β eutectoid forming element. This alloy exhibits good formability and weldability as unalloyed pure titanium with improved thermal mechanical properties particularly at slightly elevated temperatures, roughly 350 ℃. Ti-2.5Cu alloy is mainly used as all sorts of components such as bypass ducts of gas turbine engines of aircrafts.The relationships among heat treatment, microstructure and properties heve been investigated. Transmission electron microscopy and optical microscopy have been employed to observe microstructures. Vickers hardness and tensile strength were determined after different heat treatments such as annealing and aging. The results show that the best annealing temperature is 790 ℃±10 ℃. A two step aging treatment of 8 h, 400 ℃ + 8 h, 475 ℃ which leads to the formation of Ti 2Cu precipitates has been adopted in order to cut down aging time. An optimized strengthening effect has been achieved with the Ti 2Cu particles grown up to 100 nm after this two step aging.