Phase stability and its effect on tensile properties of MAR-M247 alloy have been investigated during thermal exposure at 800–900 °C for up to 10,000 h. Detailed investigations reveal that the larger secondary γ′ phase has no obvious growth, but the smaller tertiary γ′ phase obviously coarsens and the coalescence occurs during thermal exposure at 850 °C and below. γ′ coarsening behavior is consistent with the description of Ostwald ripening theory before γ′ coalescence. Hf-rich blocky MC carbide shows excellent thermal stability, but Ta-rich script-type MC carbide gradually degenerates via reaction, MC + γ → M₂₃C₆ + γ′ and finally forms γ׳ film around MC and M₂₃C₆ carbides. With increasing thermal exposure time, the tensile strength decreases. The ductility first increases and then decreases during exposure at 800 °C, but it decreases continuously at 900 °C. In addition, the ductility keeps almost constant when the exposure time is longer than 5000 h.

在800–900°C的热暴露下长达10,000 h的过程中，已经研究了MAR-M247合金的相稳定性及其对拉伸性能的影响。详细的研究表明，较大的次生γ '相没有明显的生长，但是较小的三次生γ '相则明显变粗，并且在850°C及以下的热暴露过程中发生了聚结。γ '的粗化行为与γ '合并之前的奥斯特瓦尔德熟化理论的描述是一致的。富H的块状MC碳化物表现出优异的热稳定性，但富钽的脚本型MC碳化物通过反应逐渐退化，MC +  γ  →M ₂₃ C ₆  +  γ′，最后在MC和M ₂₃ C ₆碳化物周围形成γ ׳膜。随着热暴露时间的增加，拉伸强度降低。延展性在暴露于800°C时先增加然后降低，但在900°C时则连续降低。此外，当暴露时间超过5000小时时，延展性几乎保持不变。