【摘要】 通过真空感应熔炼(VIM)棒料+电极感应熔炼氩气雾化(EIGA)制粉+热等静压(HIP)成形+热处理(HT)工艺制备三种W含量(质量分数4.1%、6.1%和8.1%)的新型镍基粉末高温合金实验锭坯。以此锭坯为对象，结合金属材料相图计算及材料性能模拟软件JMatPro 6.5计算，利用SEM、EBSD和XRD分析W含量对热处理态锭坯显微组织(如晶粒尺寸、退火孪晶、γ′强化相及错配度)的影响，测试分析不同温度下合金的拉伸性能，通过经验公式量化分析各强化机制对合金室温屈服强度的贡献情况。结果表明，随着W含量增加，γ基体层错能明显降低，热处理态退火孪晶界Σ3数量增多；W促使晶内一次γ′强化相由立方状加速粗化为固态枝晶状，对γ′总量和二次、三次γ′的影响不大；W进入γ基体产生晶格畸变的程度大于γ′强化相，使得γ′/γ错配度呈下降趋势；W有助于提高室温和650～800℃拉伸强度，但略微降低塑性；W主要起固溶强化、γ/γ′共格应变强化和晶界强化作用，其中固溶强化贡献相对最低，固溶强化时以强化γ基体为主，γ基体固溶强化和γ/γ′共格应变强化效果随W含量增加而减弱，W含量为6.1%时晶界强化效果最大；固溶强化、γ/γ′共格应变强化和晶界强化贡献值总和不足室温屈服强度实测值的50%,合金以γ′相沉淀强化为主，测试值和计算值较为吻合。更多还原

【Abstract】 Three experimental high-strength Ni-based PM superalloy ingots with different W contents(4.1wt%, 6.1wt%, and 8.1wt%) were prepared by the process of vacuum induction melting(VIM) + electrode induction melting gas atomization(EIGA) + hot isostatic pressing(HIP) + heat treatment(HT). Combined with the software JMatPro 6.5 and SEM, EBSD, and XRD, the effects of W content on the grain size, annealing twin boundaries, the γ′ phase and the lattice mismatch were analyzed, and the effect of W content on the tensile properties at different temperatures were also calculated and studied. The results indicated that the stacking fault energy of the γ matrix decreased significantly with the increase of W content, resulting in the increase of Σ3 annealing twin boundaries; W transformed the shape of primary γ′ from cuboid to solid state dendrite, but had little impact on the total amount of γ′ phase and secondary and tertiary γ′ phases; the degree of lattice distortion caused by W entering γ phase is greater than that of γ′ phase, resulting in a decrease of the γ′/γ lattice mismatch; W contributed to improving the tensile strength at room temperature and 650—800 ℃, but slightly reduced the ductility. W had better strength above 750 ℃, and it was widely added in the fourth generation PM superalloys. W mainly played the role of solid solution strengthening, γ/γ′ coherent strain strengthening, and grain boundary strengthening. Among them, the contribution of solid solution strengthening was relatively low and W mainly strengthened the γ matrix. The effect of γ matrix solution strengthening and γ/γ′ coherent strain strengthening decreased with the increase of W content, and the grain boundary strengthening effect was the largest when W content was 6.1%. The total contribution of solid solution strengthening, γ/γ′ coherent strain strengthening and grain boundary strengthening was less than 50% of the measured yield strength at room temperature, which indicated that the alloy was mainly strengthened by the γ′ phase.更多还原