一种含Re单晶镍基合金的中温蠕变行为及影响因素

Creep Behavior and Its Effect Factors of a Single Crystal Nickel-Based Superalloy Containing 4.5%Re at Medium Temperature

摘要:

通过对合金进行不同温度的固溶处理、蠕变曲线测定及组织形貌观察，研究了热处理工艺对4.5%Re镍基单晶合金中温蠕变行为的影响。结果表明：随着固溶温度提高，可降低元素的偏析程度，提高合金的蠕变性能。在760 ℃/800 MPa条件的蠕变期间，合金中γ′相不形成筏状组织，但在近断口区域，立方γ′ 相的扭曲程度增加。合金在蠕变期间的变形特征是位错在基体中运动和剪切γ′相，其中，切入γ′ 相的<110>超位错可由 {111} 面交滑移到 {100} 面，形成K-W锁，而切过γ′相的<110>超位错在 {111} 面发生分解，可形成 (1/3)<112> 超肖可莱不全位错+层错的位错组态，阻碍位错运动和抑制位错的交滑移

Abstract:

The influence of heat treatment techniques on medium temperature creep behaviors of the 4.5%Re single crystal nickel-base superalloy with different heat treatment regimes was investigated by means of creep curve measurement and microstructure observation. Results show that the creep property of the alloy is obviously improved with enhancing the solution temperature due to decreasing the segregation extent of the elements. After fully heat treated, the microstructure of the alloy consists of the cubic g￠ phase embedded coherent in the g matrix. During creep under the condition of 760 °C/800 MPa, no rafted structure of g￠ phase is detected, but the twisted configuration of the g￠ phase is formed in the regions near the fracture. In the ranges of the applied stresses and temperatures, the alloy displays a better creep resistance and a longer creep lifetime. And the deformation features of the alloy during creep are that the dislocations move in the g matrix channels and shear into the g￠ phase, the <110> super-dislocation shearing into the g￠ phase can be cross-slipped from {111} planes to {100} planes to form K-W locking, or the <110> super-dislocation shearing into the g￠ phase is decomposed to form the configuration of (1/3)<112> super-Shockleys partials plus the stacking fault, which may hinder dislocations movement and restrain the cross-slipping of dislocations. This is thought to be the main reason of the alloy having a better creep resistance