摘要
研究了一种[001]取向镍基单晶合金的蠕变特征和变形期间的微观组织结构.结果表明:在低温高应力和高温低应力条件下,合金具有较长的蠕变寿命和较低的稳态蠕变速率;在700℃,720MPa条件下,透射电镜(TEM)观察显示蠕变期间的变形特征是1/2<110>位错在基体中运动,发生反应形成1/3<112>超肖克利(Shockley)不全位错,切入γ′相后产生层错.在900℃,450MPa条件下,没有出现蠕变初始阶段,γ′相从立方体形态演化成筏形;在加速蠕变阶段,多系滑移开动,大量位错剪切γ′相是变形的主要机制.在1070℃,150MPa条件下,γ′相逐渐转变成筏形组织,并在γ/γ′界面处形成致密的六边形位错网,位错网可以阻止位错切入γ′相,提高蠕变抗力;在蠕变后期,位错以位错对形式切入γ′相,是合金变形的主要方式.
An investigation was conducted on the creep behavior and microstructure of a Ni base single crystal superalloy with [001] orientation during creep deformation.The results show that the test samples exhibited a lower steady creep rate and a longer creep life under the higher temperature and stress level.Under the condition of 700℃ and 720MPa TEM observations indicate that 1/2〈110〉 dislocations move in the matrix and react to form the Shockley segments of 1/3〈112〉 dislocations,which cut into the γ＇ phase and form stacking faults in the precipitates.Under the condition of 900℃ and 450MPa,the primary creep stage does not appear.The morphological evaluation of the γ＇ phase develops from original cubic to raft microstructure.Multiple slip operates and dislocations shearing the γ＇ phase is the main deformation mechanism during the creep acceleration stage.Under the condition of 1070℃ and 150MPa,it is found that the γ＇ phase gradually changes into raft microstructure,hexagonal dislocation networks appear on the γ/γ＇ interface,and the regular and dense dislocation networks can inhibit dislocations cutting into the γ＇ phase and enhance the creep resistance.In the later creep stage,the main deformation characteristic is that the γ＇ phase is sheared by dislocation pairs.
出处
《北京科技大学学报》
EI
CAS
CSCD
北大核心
2010年第11期1459-1463,1488,共6页
Journal of University of Science and Technology Beijing
关键词
高温合金
镍合金
单晶体
蠕变
位错
superalloys
nickel alloys
single crystals
creep
dislocations
