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我国自主研发的低成本DD6镍基高温合金,具有优良的拉伸性能和高温蠕变性能等,在涡轮机部件等领域具有广阔的应用前景。本研究从建立单晶叶片使用失效评价方式的角度出发,模拟叶片实际使用温度对DD6进行了加热处理,研究和分析了DD6合金在模拟使用温度下保温50 h后微观组织随温度的演化规律。研究发现,在模拟使用状态加热的过程中,随加热温度的升高,γ′相首先发生连接、合并,尺寸不断增大,随后向γ基体中溶解,这与Al、Nb等γ′相形成元素从γ′相向γ基体中的扩散有关。加热到1150℃以上在冷却到室温的过程中,较宽的基体通道内会析出颗粒状的二次γ′相,且二次γ′相颗粒随着加热温度的升高进一步长大。二次γ′相的析出是因为γ基体中Al、Nb元素过饱和引起了成分过冷,而其长大从热力学上看是为了减小界面能,从动力学上看与加热温度及长大时间有关。
China’s independent research and development of low-cost DD6 nickel-based superalloy, with excellent tensile properties and high temperature creep properties, etc., in the turbine components and other fields has broad application prospects. In this study, DD6 was simulated by simulating the actual temperature of the blade, and the evolution of the microstructure of the DD6 alloy at 50 h simulated temperature was studied and analyzed from the point of view of establishing the failure mode of single-crystal blade. The results show that the γ ’phases are firstly connected, merged and the size increases with the increase of the heating temperature in the simulated heating state, which then dissolves into the γ matrix, which forms with the γ’ phase of Al and Nb The element is related to the diffusion from the γ ’phase to the γ matrix. Heating to more than 1150 ℃ During cooling to room temperature, a wide range of matrix channels will precipitate particulate secondary γ ’phase, and the secondary γ’ phase particles grow with the heating temperature further. Secondary γ ’phase precipitation is due to gamma matrix Al, Nb element supersaturation caused by the composition is too cold, and its growth from the thermodynamic point of view is to reduce the interfacial energy, from the kinetic point of view and heating temperature and growth Time related.