研究了一种定向凝固镍基高温合金在870℃，330—420MPa应力下的高温拉伸蠕变性能．结果表明：蠕变曲线表现了较短的减速蠕变阶段和较长的加速蠕变阶段，其蠕变变形机制为位错在第二相粒子间的Orowan弯曲过程，而不是由扩散过程所控制加速蠕变阶段蠕变速率的起始增加是显微组织发生变化（γ’相的定向粗化）的结果，而不是蠕变裂纹的形成与扩展．蠕变断裂数据符合MonkmanGrant关系．最终的断裂过程受控于蠕变裂纹的扩展速度
The tensile creep behaviors of DZ17G alloy, a directionally soliditied Ni-base superalloyl were investigated at 870 ℃ under the applied stress range of 330-420 MPa. All of the creep curves have similar shape: a short primary creep and dominant accelerated creep stages. The creep apparent parameters (the stress exponent and the apparent activation energy for creep) and TEM observations suggest that the Orowan bowing process of dislocations is the dominant creep deformation mechanism. The reason why creep rate ascends at the beginning of accelerated creep stage is not the nucleation and propagation of creep cracks, but the consequence of microstructure change (γ' particles oriented coarsening uncompletely). The creep fracture data follow the Monkman-Grant relationship, and the final fracture process is controlled by the propagation rate of creep cracks.
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