NiAl/TiAl基梯度合金空心结构电流辅助构筑烧结形性协同控制基础研究

In order to meet the urgent needs of light heat-resistant materials and their complex components for advanced aeronautical supersonic aircraft engines and to replace currently widely used high-density Ni based superalloys, in this project, aiming at near-net forming of nozzle-like hollow structure for turbine engines, a new route combined with current-assisted constructed sintering and synergetic control of shape and property for NiAl/TiAl based gradient alloy has been offered, which can break the technical bottleneck of intermetallics and their gradient alloys with difficulty in forming and machining. Based on the study of densification mechanism in current-assisted constructed sintering, the evolution for microstructure and property of the alloy under coupled energy field will be further investigated. Meanwhile, the diffusion bonding mechanism of metallic powders during sintering will also be revealed systematically, which can clarify the relationships among the constructed sintering, diffusion bonding, microstructure evolution, and performance optimization. On the basis of near-net sintering, the integrated heat treatment will also be realized, resulting in a simplified processing step and synergetic controlling of shape and property. The expected achievements will provide theoretical and experimental details for resolving the core-scientific problem “the effect of special/coupled energy field on high-temperature materials and the synergetic control mechanism of shape and property” in the manufacturing of key-components for aeroengine in China. Moreover, this project will further help to enhance the original innovation ability and international influence of advanced manufacturing technology for aeroengine high-temperature materials in China.

为满足航空超音速飞行器先进发动机对轻质耐热材料及其复杂构件的迫切需求，以替换目前广泛使用的大密度Ni基高温合金为目的，本项目针对涡轮发动机喷管类空心结构近净成形，提出NiAl/TiAl基梯度合金电流辅助构筑烧结-形性协同控制的新思路，突破金属间化合物及其梯度合金难成形、难加工的技术瓶颈。揭示电流辅助构筑烧结致密化机理，明晰复合能场作用下材料组织性能演变规律，阐明粉末材料烧结扩散连接机制，构建构筑烧结-扩散连接-组织演变-性能优化之间的内在联系。在近净烧结成形基础上，实现一体化热处理、简化工艺步骤、调控组织性能，达到形性协同控制的目的。为解决我国航空发动机关键构件制造中“特种/复合能场对高温材料的作用及形性协同控制机理”核心科学问题提供理论与实验依据，进而提升我国航空发动机高温材料先进制造技术的原始创新能力和国际影响力。

本项目以航空新一代发动机喷管为应用背景，以轻质耐热NiAl/TiAl基合金替代现有Ni基高温合金轻量化减重为目的，采用快速凝固方法制备了NiAl/TiAl基合金粉末，建立了复合能场烧结参数与烧结态合金致密度之间的关系，优化了复合能场烧结成形参数。基于微观组织分析及数值模拟结果，揭示了金属间化合物合金粉末复合能场作用下的宏微观变形及原子扩散致密化过程与机理。对不同烧结工艺参数条件下NiAl基、TiAl基合金材料的微观组织及力学性能进行了系统的研究，阐明了复合能场烧结合金组织性能演变规律。对烧结NiAl基、TiAl基合金的力学性能进行了优化与调控，NiAl基合金1000°C抗拉强度达397.2MPa，TiAl基合金800°C抗拉强度达584.8MPa。研究了烧结温度、初始烧结材料致密度、结合层粗糙度等参量对构筑烧结连接合金致密度及微观组织的影响规律，分析了同种及异种烧结连接合金的力学性能，优化了烧结连接工艺参数。对NiAl基、TiAl基金属间化合物空心结构烧结连接方法及工艺进行了研究，制备了NiAl基、TiAl基金属间化合物空心筒形件。采用构筑烧结连接的方法，制备了典型管件外径≥50mm，管件外径与壁厚比≥10，管件长度与外径比≥1.5的NiAl基合金空心筒形件。所取得的研究结果为解决我国航空发动机关键构件制造中“特种/复合能场对高温材料的作用及形性协同控制机理”核心科学问题提供了理论与实验依据，有助于提升我国航空发动机高温材料先进制造技术的原始创新能力和国际影响力。