一种单晶合金的高温循环断裂变形行为

High Temperature Cyclic Fracture and Deformation Behavior of a Ni-Base Single Crystal Superalloy

系统研究了DD499单晶合金950℃应变控制的低周疲劳循环断裂变形行为。研究表明,高温氧化不但加速了裂纹在试样表面萌生,而且也促进了裂纹沿[110]方向扩展,合金低周疲劳的失效可归因于氧化、蠕变和疲劳破坏累积的共同作用结果。950℃循环应力响应为位错之间、位错与γ'沉淀相颗粒之间、位错与碳化物之间的交互作用的共同强化结果。950℃低周疲劳变形机制由位错剪切向位错攀移进行转变。

Low-cycle fatigue(LCF)cyclic fracture and deformation behaviors were systemically investigated at 950℃on DD499 single crystal superalloy.It is shown that high temperature oxidation not only accelerates the initiation of crack at the surface,but also promotes the crack propagation along[110]direction.The low-cycle fatigue failure occurs under the combined action of oxidation,creep and fatigue.The cyclic stress response behavior at 950℃can be taken as the result of interactions between dislocation-dislocation,dislocation-γ′precipitate,dislocations and carbides.Low cycle fatigue deformation mechanism at 950℃is transiting from dislocations shearing to dislocation climb.