论文部分内容阅读
研究了DZ444和IN738两种铸造镍基高温合金在不同温度下的热疲劳行为,利用光学(OM)和扫描电镜(SEM)等手段研究了两合金在热疲劳过程中的微观组织变化。结果表明,850℃时,热疲劳过程对两合金的微观组织影响不大,两合金的组织稳定。900℃时,DZ444合金的γ′形貌发生轻微不规则化,尤其在裂纹附近比较明显,此时IN738合金的微观组织没有明显变化。950℃时,两合金的微观组织均发生演化,其中DZ444合金中的临近裂纹区域γ′发生筏形化,而IN738合金的裂纹两侧形成γ′贫化带,基体中析出二次细小γ′相,并且MC碳化物按照MC+γ→M23C6+γ′反应而退化。
The thermal fatigue behavior of two kinds of foundry nickel base superalloy DZ444 and IN738 at different temperatures was studied. The microstructure changes of the two alloys during thermal fatigue were investigated by means of optical microscope (OM) and scanning electron microscope (SEM). The results show that the thermal fatigue at 850 ℃ has little effect on the microstructure of the two alloys, and the microstructure of the two alloys is stable. At 900 ℃, the γ ’morphology of DZ444 alloy is slightly irregular, especially in the vicinity of the crack. At this time, the microstructure of IN738 alloy did not change significantly. The microstructures of both alloys evolved at 950 ℃. The γ ’depleted zone formed on both sides of the crack in IN738 alloy and the secondary fine γ’ precipitated in the matrix. Phase, and MC carbide is degraded by the reaction of MC + γ → M23C6 + γ ’.