FGH96 is a powder metallurgy nickel based superally used for turbine disk of aero-engines. In the present study FGH96 alloy with four different γ′ precipitate microstructures were produced via solution heat-treatment with different cooling rates, and the maximum cooling rate reached 400 ​°C/min which was a super cooling rate for Nickel-based superalloy. The creep tests were conducted for PM FGH96 alloy under the testing condition of 704 ​°C and 690 ​MPa. The relationship between the creep properties and the distribution of γ’ precipitate was established. The creep mechanism was analyzed by using TEM and ACTEM, and the dislocation movement was studied at the atomic scale. The creep strain rate was calculated through a physically based crystal slip model established based on crystal plasticity. The calculated results were consistent with the test ones, illustrating the validity of the model. The fracture mechanism was also investigated, and the results showed that the creep cracks generated on the surface due to the oxidation. It was observed that the cracks propagated in different ways depending on the different average diameters of ​γ′ ​precipitate. With the decrease of the average ​γ’ ​precipitate size, the critical shearing stress increased and the resistance of the dislocation slipping increased. The fracture mechanism for the primary stage transformed from intragranular to intergranular due to the change of dislocation slipping.

FGH96是一种粉末冶金镍基合金，主要用于航空发动机的涡轮盘。在本研究中，通过固溶热处理以不同的冷却速率生产出具有四种不同γ'析出物组织的FGH96合金，最大冷却速率达到400°C / min，这是镍基高温合金的超级冷却速率。PM FGH96合金在704°C和690 MPa的测试条件下进行了蠕变测试。建立了蠕变性能与γ'沉淀物分布之间的关系。用TEM和ACTE分析了蠕变机理，并在原子尺度上研究了位错运动。通过基于晶体可塑性建立的基于物理的晶体滑动模型来计算蠕变应变率。计算结果与测试结果一致，说明模型的有效性。还研究了断裂机理，结果表明，由于氧化作用，在表面产生了蠕变裂纹。观察到裂纹根据γ′沉淀物的不同平均直径以不同的方式传播。随着平均γ'沉淀尺寸的减小，临界剪切应力增大，位错滑移的阻力增大。由于位错滑移的变化，初生阶段的断裂机制从粒内转变为粒间。观察到裂纹根据γ′沉淀物的不同平均直径以不同的方式传播。随着平均γ'沉淀尺寸的减小，临界剪切应力增大，位错滑移的阻力增大。由于位错滑移的变化，初生阶段的断裂机制从粒内转变为粒间。观察到裂纹根据γ′沉淀物的不同平均直径以不同的方式传播。随着平均γ'沉淀尺寸的减小，临界剪切应力增大，位错滑移的阻力增大。由于位错滑移的变化，初生阶段的断裂机制从粒内转变为粒间。