Ni3Al基高温合金瞬时液相扩散连接接头组织演变及可靠性评价

Ni3Al基高温合金作为高温结构材料在航空航天等领域得到广泛的研究和应用。但高的Al+Ti元素含量，使得Ni3Al基高温合金可焊性差，合金热裂敏感性和焊接开裂倾向严重。瞬时液相（TLP）扩散连接技术可实现Ni3Al基高温合金构件的良好连接，而确保Ni3Al基合金接头高温持久强度与母材相当是构件安全可靠服役的关键。据此，本项目拟通过分析Ni3Al基高温合金TLP扩散连接过程溶质原子迁移、非平衡偏聚以及相析出与演变的动力学行为，揭示接头组织的形成机制；澄清服役条件下（正常工况、超温、超载）接头组织退化行为和蠕变断裂微观机制；以接头蠕变强度退化为衡量标准，调整中间层成分和优化TLP扩散连接工艺参数，对TLP扩散连接接头组织进行调控和可靠性评价；在此基础上，构建TLP扩散连接工艺、接头组织、蠕变断裂三者的特征关系。

Ni3Al-based superalloys have been widely studied and applied in aerospace and other fields as high-temperature structural materials. However, the high contents of Al and Ti make Ni3Al-based superalloys poor in weldability, and the alloys' sensitivity to thermal cracking and their tendency to weld cracking are serious. Transient liquid phase (TLP) diffusion bonding can achieve good connection of Ni3Al-based superalloy components. And the high-temperature durability of joints is comparable to the base material, which is the key to safe and reliable service of the components. Based on this, this project intends to reveal the formation mechanism of the joint structure by analyzing the dynamics of solute atom migration, non-equilibrium segregation, and phase precipitation and evolution during the TLP diffusion bonding process of Ni3Al-based superalloys. The joint degradation behavior and creep fracture mechanism under service conditions (normal conditions, overtemperature and overload) will be clarified. Taking joint creep strength degradation as a measure, the composition of the middle layer and the TLP diffusion bonding process parameters are optimized to regulate and evaluate the joint structure. On this basis, the characteristic relationship of the TLP diffusion bonding process, joint structure, and creep fracture is established.