摘要
通过对一种4.5%Re(质量分数)镍基单晶合金进行不同工艺热处理、蠕变性能测试及组织形貌观察,研究了固溶时间对该合金组织结构与高温蠕变行为的影响。结果表明:铸态合金中各元素存在较大的成分偏析,经高温长时间固溶及时效处理后,合金中各元素在枝晶间/臂的偏析程度明显降低;将固溶时间由10 h延长至24 h后,合金在1100℃、137 MPa的蠕变寿命由101 h提高至164 h;其中,10 h固溶处理合金中仍存在较大程度的元素偏析,并且在蠕变期间,析出针状TCP相。合金在高温蠕变期间的变形机制是位错在基体中滑移和剪切筏状γ′相;蠕变后期,大量位错剪切筏状γ′相,致使近断口区域的筏状γ′相扭曲,在筏状γ/γ′两相界面发生裂纹的萌生,并沿垂直于应力轴方向扩展,直至发生蠕变断裂。这是合金的高温蠕变断裂机制。
By means of heat treatment at different regimes and creep property measurement, combining with microstructure observation, the effects of the solution time on the microstructure and creep behaviors of a 4.5%Re（mass fraction） nickel-based single crystal superalloy at high temperature were investigated. The results show that the segregation extent of the elements in the as-cast alloy may be obviously reduced by means of heat treatment at high temperature. When extended the solution time from 10 h to 24 h, the creep life of the alloy enhances from 101 h to 164 h. Thereinto, bigger segregation extent of the elements appears still in the alloy treated by technique 1, which results in the precipitation of the needle-like TCP phase. The deformation mechanism of the alloy during creep is dislocations slipping in the γ matrix and shearing into the rafted γ′ phase. At the later stage of creep, the significant amount of dislocations shearing into the rafted γ′ phase results in the twist of the rafted γ′ phase, which may promote the initiation and propagation of the micro-cracks at the interfaces of γ/γ′ phases up to the occurrence of creep fracture. This is thought to be the fracture mechanism of alloy during creep at high temperature.
出处
《中国有色金属学报》
EI
CAS
CSCD
北大核心
2015年第6期1480-1489,共10页
The Chinese Journal of Nonferrous Metals
基金
国家自然科学基金资助(51271125)
关键词
单晶镍基合金
RE
TCP相
元素偏析
蠕变
nickel-base single crystal superalloy
Re
TCP phase
element segregation
creep
作者简介
通信作者：田素贵，教授，博士；电话：024—25494089；传真：024—25496768：E-mail：tiansugui2003@163．com
