热过程对IC21单晶合金组织和力学性能的影响

利用光学显微镜和扫描电镜对IC21单晶合金的铸态、热处理后和不同热过程后的组织进行了观察,检测了铸态、热处理态和不同热过程后合金的高温拉伸和持久性能,研究了热处理和热过程对IC21合金组织演变和力学性能的影响。结果表明,IC21合金的铸态组织呈树枝晶状,由γ′相、γ相以及枝晶间的粗大γ′相和NiMo相组成,枝晶干上γ′相尺寸比枝晶间的γ′相尺寸大。1315 ℃/6 h/充氩冷却+两次时效热处理后合金未实现完全固溶,枝晶干上部分铸态γ′相在固溶时未完全溶解,枝晶间仍存在粗大γ′相,持久性能与铸态相比有明显提升。热过程后,γ′相明显长大,立方度略有降低,枝晶间和枝晶干的γ′相尺寸差距减小,并且有针状相析出。合金的持久寿命与热处理态相比,稍有降低,抗拉强度有所提高。

Effect of thermal process on microstructure and mechanical properties of IC21 single crystal alloy

Microstructure of the IC21 single crystal alloy at as-cast state, after heat treatment and after different thermal processes were observed by optical microscope(OM) and scanning electron microscopy(SEM).The high-temperature tensile and enduring properties of the alloy at as-cast, heat treated and various thermal processes treated state were tested. The effects of heat treatment and thermal process on microstructure evolution and mechanical properties of the IC21 alloy were studied. The results show that the as-cast alloy is dendritic growth and consisted of γ′ phase, γ phase, bulky γ′ in the interdendritic regions and NiMo phase. The size of γ′ phase in the dendrite region is larger than that in the interdendritic region. The alloy is not complete solid solution after 1315 ℃/6 h/argon cooling and two aging treatment, and the γ′ phase in the dendrite is not completely dissolved. There are still coarse γ′ phases between dendrites. The high temperature rupture properties of the alloy are obviously improved. The γ′ phase grows up obviously and the cubic degree decreases slightly after thermal process. After thermal process, the size difference of γ′ phase between dendrites and interdendrites decreases, and needle phase precipitates. Compared with the heat treatment state, the endurance life of the alloy is slightly reduced, but the tensile strength is improved.