利用Thermo-Calc热力学计算软件和TTNi7镍基高温合金数据库, 研究了Re元素对Ni-20Cr-10Al-20Co合金体系相组成的影响规律.在热力学计算的基础上, 设计了4组不同Re含量的NiCoCrAlY涂层合金, 进行了不同温度的热暴露实验. 研究结果表明, Re的添加, 小幅度地提高了β-NiAl相的含量, 且改变了Cr在各相中的分配, 促进了富Cr的低温稳定相σ和高温稳定相α-Cr的析出, 且σ→α-Cr的相变温度随Re含量的增加而升高. 此外, 实验结果还显示, Re的添加降低了γ’-Ni₃Al→γ-Ni的相变温度. 对比计算结果和实验结果可发现, TTNi7数据库对MCrAlY合金在相组成演变规律方面的预测与实验结果符合较好, 但在具体的相变温度方面,如γ’-Ni₃Al→γ-Ni和σ→α-Cr的相变温度,与实验结果还存在较大偏差.

MCrAlY alloy has served as overlay coatings or bond coats in thermal barrier coating systems ingas turbine engines, and its phase constituents play a vital role in determining the performance of these coatingsystems. In order to further understand the influence of Re on the phase constituents of MCrAlY coatings, the phase evolution of a Ni-20Cr-10Al-20Co coating alloy with 0-9% (mass fraction) Re addition was predicted the Thermo-Calc thermodynamic software and TTNi7 Ni-based superalloy database. Based on the calculation results,the four NiCoCrAlY alloys with different levels of Re (0, 3%, 6% and 9%) were prepared, and their phase constituents were experimentally investigated in the temperature range of 800-1250℃. Both the calculation result and the experimental microstructural observation indicated that the addition of Re slightly increased the fraction of β-NiAl phase, but dramatically enhanced the amounts of σ and α-Cr phases. Based on the combined analysis of microstructural observation and EPMA composition identification, it was proposed that the increased amounts of σ and α-Cr phases should result from the changed partition of Cr in all phases caused by Re addition. The σ phase is a low temperature stable phase, and would change to α-Cr phaseas temperature rises. The transformation temperature of σ→α-Cr phase increases as the addition of Re increases.The experimental results also showed that the γ’-Ni₃Al→γ-Ni transformation temperature decreases with the addition of Re. In addition, the calculation results were compared with the experimental results and were found to be in reasonable agreement with the experimental observations from the aspect of the MCrAlY phase evolution. Some deviations of the calculation and experiment results about the precise phase-change temperatures, such as γ’-Ni₃Al→γ-Ni and σ→α-Cr phase transformation temperatures, were observed, and the reason were discussed in the light of both limited availability of thermodynamic database and experimental problems.