The coarsening behavior of the γʹ precipitates and compression deformation mechanism of the γʹ-strengthened CoNi-base superalloys are investigated. By substituting 1 at.% Ta for 1 at.% W, the 4W2Ta alloy exhibits a higher γʹ solvus temperature of 1218 °C and a lower mass density of 8.93 g/cm³. During the aging process from 900 to 1000 °C, both of the 5W1Ta and 4W2Ta alloys show stable γ/γʹ two-phase microstructure. The coarsening behavior of the γʹ precipitates in the two alloys follows the classical Lifshitz-Slyozov-Wagner (LSW) model. The coarsening rate constant of the 4W2Ta alloy is approximately two times lower than that of the 5W1Ta alloy, which is attributed to its larger lattice mismatch due to the addition of Ta. Besides, compared with the 5W1Ta alloy, the 4W2Ta alloy has higher high-temperature strength and shows different deformation behavior. When the deformation temperature is lower than 800 °C, pairs of dislocations shear the γʹ precipitates and γ matrix. At 800 °C, stacking faults (SFs) appear in the γʹ precipitates and increase with the increasing temperature, whereas most of dislocations bypass the γʹ precipitates at 1000 °C.

研究了γʹ强化CoNi基高温合金γʹ析出物的粗化行为和压缩变形机制。通过用 1 at.% Ta 代替 1 at.% W，4W2Ta 合金表现出更高的 γʹ 固溶温度为 1218 °C，质量密度更低，为 8.93 g/cm ³. 在 900 到 1000 °C 的时效过程中，5W1Ta 和 4W2Ta 合金均显示出稳定的 γ/γʹ 两相显微组织。两种合金中 γʹ 析出物的粗化行为遵循经典的 Lifshitz-Slyozov-Wagner (LSW) 模型。4W2Ta 合金的粗化速率常数比 5W1Ta 合金低约两倍，这是由于添加了 Ta 导致晶格失配较大。此外，与5W1Ta合金相比，4W2Ta合金具有更高的高温强度并表现出不同的变形行为。当变形温度低于800℃时，位错对剪切γ′沉淀物和γ基体。在 800 °C 时，γʹ 析出物中出现堆垛层错（SFs），并随着温度的升高而增加，