摘要
为了降低U720Li镍基合金锻造强度,通过改变γ'相的组织形态和析出数量的方法,研究1130℃下保温10、20和30 h后γ'相的析出形态、体积分数和显微硬度的影响,并对其进行1100～1170℃,变形速率1.0 s-1和50%变形量的热变形。结果表明,当保温30 h后,合金中γ'相形貌由方形向圆形转变,γ'相尺寸长大,体积含量最小,具有较小的流变应力。在1130℃保温30 h条件下,当变形温度低于1150℃时,析出的γ'相数量越多,对位错的阻碍作用越强烈,流变抗力越大;当变形温度超过1150℃时,合金中γ'相溶解,此时变形温度越高,合金的流变抗力越低。同时在较低温度下变形,因γ'相对晶界迁移的阻碍作用,再结晶晶粒尺寸较小,而在高温下变形再结晶晶粒长大,温度越高,再结晶晶粒越大。
The coarsening behavior of γ＇ precipitates in U720Li superalloy heated at 1130℃ for different time was investigated and the effect of γ＇ precipitation behavior on decreasing hot deformation resistance of the U720Li alloy was examined by hot compression tests at 1100-1170 ~C with strain rate of 1.0 s-1, and deformation amount of 50%. The results show that with increasing holding time, the amount of small γ＇ particles is decreased, and the γ＇ particles are coarsened because of the Oswald ripening. Soaking at 1130℃ for 30 h, the γ＇ phase is enlarged and its morphology changes from cubic to circular, the volume fraction of γ＇ phase, reaches minimum, and the deformation resistance of the alloy is decreased. For the samples soaked at 1130℃ for 30 h, the hot compression tests with strain rate of 1.0 s-1 in the temperature range of 1100 ℃ to 1170℃ were conducted. The results reveal the relationship between the γ＇precipitates and flow stress, Compressing below 1150, the enhanced precipitation of γ＇ precipitates inhibits the movement of dislocations, therefore, the flow stress is increased. Above 1150℃ , 3＂ precipitates are dissolved, and the flow stress decreases with the deformation temperature increasing. The γ＇ precipitates block the grain boundary migration, as a result, the recrystallized grain size is bigger in the sample deformed at high temperature.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2013年第3期50-54,共5页
Transactions of Materials and Heat Treatment
基金
国家自然科学基金(50271072)
关键词
γ'相
U720Li合金
热变形
位错
再结晶
γ＇ phases
U720Li alloy
hot deformation
dislocation
recrystallization
