The aim of the present investigation is to study the tensile creep behavior of nickel-based disk superalloy, which is widely used in the manufacturing of turbine disks for the aero engines. Tensile creep tests were performed over a wide range of stresses (100–900 MPa) and temperatures (625–850 °C) and rupture time varies from 93.1 to 9473 h. Furthermore, stress rupture strength was predicted using the time-temperature parameter at different temperatures for longer durations. The stress dependence of minimum creep rate for the alloy is found to follow the power law. The stress exponent (n) decreased from 31.2 to 7.8 with increase in the test temperature from 625 °C to 700 °C. Subsequently, the rate-controlling mechanism of creep is identified as dislocation climb by adopting the threshold stress analysis in the temperature range of 625–700 °C. At higher temperature, the n values are drastically reduced to 2.9, 2.7 and 2.2 at 750, 800 and 850 °C, respectively, due to dislocation annihilation and dissolution of precipitates. This indicates that the rate-controlling mechanism of creep changes from viscous glide to grain boundary sliding (n = 2.2). The activation energy for creep $\left(Q_C\right)$ has been determined by using the modified power law in the temperature range of 625–700 °C and is found to be 598 kJ/mol, whereas the obtained $Q_C$ is also decreased significantly to 435 kJ/mol at higher temperature range (750–850 °C). The calculated $Q_C$ values are found to be 52.5% and 34.7% higher than the activation energy for lattice self-diffusion of nickel (284 kJ/mol). Post creep microstructural examination using transmission electron microscopy (TEM) revealed extensive deformation in the microstructure is accommodated through the γ′ precipitates, formation of stacking faults and deformation twins within the larger γ′ precipitates. The major findings are well in strong agreement with the hardness characterization, where prominent increase in hardness within localized deformation is mainly due to extensive dislocation-interactions with the γ′ precipitates.

本研究的目的是研究广泛用于制造航空发动机涡轮盘的镍基盘状高温合金的拉伸蠕变行为。拉伸蠕变试验在广泛的应力 (100–900 MPa) 和温度 (625–850 °C) 下进行，断裂时间从 93.1 到 9473 小时不等。此外，使用不同温度下的时间-温度参数在更长的时间内预测应力断裂强度。发现合金的最小蠕变速率的应力依赖性遵循幂律。应力指数 ( n) 随着测试温度从 625 °C 增加到 700 °C，从 31.2 下降到 7.8。随后，通过在625-700°C的温度范围内采用阈值应力分析，将蠕变的速率控制机制确定为位错爬升。在较高温度下，由于位错湮灭和析出物溶解，n值分别在 750、800 和 850 °C 时急剧降低至 2.9、2.7 和 2.2。这表明蠕变的速率控制机制从粘性滑移到晶界滑移（n  =  2.2）。蠕变的活化能$\left({问}_C\right)$ 已在 625–700 °C 的温度范围内使用修正的幂律确定，结果为 598 kJ/mol，而获得的 ${问}_C$在较高的温度范围 (750–850 °C) 下，也显着降低至 435 kJ/mol。计算出的${问}_C$发现值比镍的晶格自扩散的活化能 (284 kJ/mol) 高 52.5% 和 34.7%。使用透射电子显微镜 (TEM) 进行的蠕变后显微组织检查显示，通过 γ' 沉淀物、在较大的 γ' 沉淀物中形成堆垛层错和变形孪晶来调节微观结构中的广泛变形。主要发现与硬度表征非常一致，其中局部变形内硬度的显着增加主要是由于与 γ' 析出物的广泛位错相互作用。