Re含量对单晶高温合金组织和拉伸性能的影响

为优化一种单晶高温合金中的Re含量，在真空定向凝固炉中制备了3%Re和5%Re的镍基单晶高温合金，热处理后分别在980 ℃长期时效400、800、2 000 h，测试合金热处理后1 100 ℃拉伸性能，采用JMatPro软件计算了合金相图，通过光学显微镜、扫描电镜和能谱仪研究Re含量对合金枝晶组织，热处理组织和980 ℃时效400、800、2 000 h的组织和1 100 ℃拉伸性能的影响。结果表明，随着单晶高温合金中Re含量增加，一次枝晶间距轻微减小，共晶的体积分数升高；γ′相尺寸下降，立方化程度增加；不同Re含量合金时效800 h后无TCP相析出，时效2 000 h后有TCP相析出，随着Re含量增加，TCP相析出量增加。合金组织稳定性随着Re含量增加而降低。随着Re含量增加，合金的高温拉伸性能显著提高。 

Effects of Re content on the microstructure and tensile properties of a single crystal superalloy

In order to optimize the Re content in single crystal superalloy, 3%Re and 5%Re nickel-based single crystal super alloys were prepared in a vacuum directional solidification furnace. After heat treatment, they were exposed to 980 ℃ for 400 h, 800 h, and 2 000 h.Besides, their tensile properties were tested when heated to 1 100 ℃.Phase diagrams of the alloys with different Re content were calculated by JMatPro software. The effects of Re contents on dendrite structure, heat treatment structure, heat treatment microstructure and their microstructure changes at different heating temperature and for different duration were investigated by optical microscope(OM), scanning electron microscope (SEM), and energy dispersive spectrometer(EDS). The results show that as the Re content in the single crystal superalloy increases, the primary dendrite spacing decreases slightly while the volume fraction of the eutectic increases.When the size of the γ′phase decreases, the degree of cubic increase. There is no precipitation of TCP phase in two alloys with different Re content after 800 hours′ heating; after heating for 2 000 h, TCP phase precipitated, and its volume fraction increased with the increase of Re content. It can also be concluded that with the increase of Re content, the stability of alloy structure decreases while the tensile properties of the alloy at high temperature significantly increase.