层错能和温度对不同Co含量的镍基高温合金蠕变性能的影响

Effects of Stacking Fault Energy and Temperature on Creep Performance of Ni-based Alloy with Different Co Contents

摘要:

研究了2种不同Co含量的镍基高温合金分别在650 °C/630 MPa，725 °C/630 MPa和760 °C/630 MPa条件下的蠕变变形组织。通过透射电镜分析了温度和层错能对蠕变变形机制的影响。结果表明，对于所选取的高温合金来说，温度的提升可以有效促使蠕变变形机制由层错转变为孪晶。这表明孪晶的形成更大程度上取决于温度。此外，合金Co含量的提升以及层错能的下降都会使层错和孪晶延伸并穿过γ基体和γ′析出相，该方式提升了材料的蠕变抗力以及蠕变寿命。

Abstract:

The deformation microstructures of two Ni-based superalloys with different Co contents after creep tests at 650 °C/630 MPa, 725 °C/630 MPa and 760 °C/630 MPa were investigated by transmission electron microscopy (TEM), in order to study the influence of temperature and stacking fault energy (SFE) on the creep deformation mechanisms. The results show that the improvement in temperature enhances the creep mechanism transition from stacking faults to micro-twinning for the experimental single crystal alloys, suggesting that the formation of micro-twins is dependent on temperature. Moreover, increasing Co content as well as lowering SFE allow stacking faults or micro-twins to extend through the γ matrix and γ′ precipitates, which improve the creep resistance and prolong the creep life of the alloys.