通过对含4.5％Re/3.0％Ru单晶镍基合金进行高温蠕变性能测试,并采用扫描电镜(SEM)、透射电镜(TEM)对不同蠕变期间的试样进行组织形貌观察,研究了该合金的高温蠕变行为.结果表明,本实验所选用的单晶合金在高温蠕变期间具有良好的蠕变抗力,在1040℃/160MPa的蠕变寿命达到725h.高温蠕变初期,合金中γ'相沿垂直于应力轴方向转变成筏状结构,其稳态蠕变期间的变形机制是位错在基体中滑移和攀移越过筏状γ'相.高温蠕变后期,合金的变形机制是位错在基体中滑移和剪切筏状γ'相.位错的交替滑移使筏形γ'相扭曲,并在γ/γ'两相界面发生裂纹的萌生与扩展直至断裂,是合金在高温蠕变后期的断裂机制.
The creep behavior of a containing 4.5％Re/3.0％Ru single crystal nickel-based superalloy at elevated temperatures was investigated by means of creep properties measurement and microstructure observations to specimens in different creep stages by SEM and TEM.Results show that the alloy exhibits good creep resistance at high temperature,and the creep life of the alloy at 1040℃/ 160MPa reaches 725h.During creep at high temperature,the γ'phase in alloy transforms into the N-type rafted structure along the direction vertical to the stress axis,the deformation mechanism of alloy during steady state creep is dislocations slipping in γ matrix and climbing over the rafted γ'phase.In the latter period of creep,the deformation mechanism of alloy is dislocations slipping and shearing into the rafted γ'phase.The alternate slipping of dislocations results in the twist of the rafted γ'phase to promote the initiation and propagation of the cracks along the interfaces of γ/γ'phases up to creep fracture,which is thought to be the fracture mechanism of alloy during creep at high temperature.
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