采用FESEM、TEM等实验技术，系统研究了750℃、600 MPa条件下，不同Ta含量的镍基粉末高温合金的蠕变性能和蠕变过程中显微组织和变形行为特征以及合金层错能对蠕变行为的影响。结果表明，随着Ta含量的增加，合金层错能呈非线性关系降低。蠕变变形各阶段的变形行为和位错组态的变化与层错能密切相关。低Ta含量合金层错能相对较高，基体位错a/2<110>滑移被阻止在γ/γ'内界面处，不易发生位错分解，可直接进入γ'相中形成反相畴界(APB)或通过Orowan环弓弯模式绕过γ'相；当合金中Ta含量中等时，合金层错能降低，促进在γ/γ'内界面处基体位错发生分解，产生a/6<112> Shockley不全位错开始剪切γ'相，形成超点阵层错(超点阵内禀层错(SISF)或超点阵外禀层错(SESF))和扩展层错(ESF)进而转化形成形变孪晶，呈现层错和形变孪晶共同强化效应，提高蠕变性能；而高Ta含量合金层错能很低，有利于位错在不同{111}滑移面上同时形成尺寸较宽的扩展层错，并出现相互交结的交叉层错抑制形变孪晶的形成，加快蠕变形变裂纹发展。因此，合金中加入适量Ta能有效降低层错能，提高形成不全位错剪切γ'相能力和形成显微孪晶能力，增加蠕变抗力，有效改善合金蠕变性能。

The nickel base powder superalloy prepared by modern powder metallurgy (PM) technology is selected because it has the characteristics of compatibility with strength and damage tolerance. Moreover, it is the preferred material for the fabrication of a new generation of aero-engine turbine disks. In this study, experimental techniques, such as FESEM and TEM, are used to systematically evaluate the creep properties of powder metallurgy nickel base superalloys with different Ta contents under the conditions of 750°C and 600 MPa. Additionally, the characteristics of microstructure and defosrmation behavior during creep and the effect of stacking fault energy of the alloy on creep property are also investigated. The results show that with increase in Ta content, the energy associated with alloy stacking fault decreases, demonstrating a nonlinear relationship. The deformation behavior and dislocation configuration changes in each creep deformation stage are closely related to the stacking fault energy. The stacking fault energy of alloys with low Ta content is relatively high, the matrix dislocation a/2<110> is prevented at the γ/γ' interface, and the dislocation is not easy to decompose. Furthermore, it can directly enter the γ' phase to form antiphase boundary or to bypass the γ' phase through the Orowan ring bow bending mode. If the alloy contains a moderate amount of Ta, the stacking fault energy of the alloy is reduced, promoting the decomposition of matrix dislocations at the γ/γ' interface. This results in a/6<112> Shockley incomplete dislocations and starts to shear the γ' phase, forming superlattice stacking faults (superlattice intrinsic stacking faults (SISFs) or superlattice extrinsic stacking faults (SESFs)) and extended stacking faults (ESFs), which are then transformed into deformation twins. Therefore, presenting the co-strengthening effect of stacking faults and deformation twins, which improves the creep property. The stacking fault energy of alloys with high Ta content is very low, which is favorable to the simultaneous formation of wide-sized ESFs on different {111} slip planes. The occurrence of inter-crossing stacking faults inhibits the formation of deformation twins and accelerates the development of creep deformation cracks. These experimental results demonstrate that the addition of an appropriate amount of Ta to the alloy can effectively reduce the stacking fault energy, improve the ability to form both partial dislocation shear γ' phase and micro-twins, increase creep resistance, and effectively improve the alloy creep property.