纳米晶种细化铝合金α-Al枝晶的动力学规律与机制

Aiming at revealing the key scientific problems in the effect and mechanism of nano-sized seeds on dendrite size and morphology of Al alloy, the thermodynamics and kinetics of the formation of nano-sized seeds from crystallization of the amorphous alloy in the melt are revealed; the kinetics effect and mechanism of nano-sized seeds on the dendrite refinement and morphology evolution are revealed; the kinetics effect and mechanism of in-situ nano-sized seeds stability on inoculation fading behavior in Al melt are revealed; the effect and mechanism of dendrite size and morphology of Al alloy refined by the amorphous alloy on the strengthening and toughening mechanism, and creep behavior in the room and elevated temperature are revealed. The relationship between the grain size and morphology of α-Al and tensile properties at room and high temperature and creep behavior was established. Solidification microstructures and service performance are controlled by nano-sized seeds from in-situ crystallization. The design criterion of amorphous alloy applied to the refinement of α-Al dendrites is proposed. It provided a theoretical basis for revealing and enriching the refinement mechanism and theory of nano-sized seeds on the dendrite refinement, expanding the scope of application of amorphous alloys, the development of a new-type, low cost and high effective refiner and a new refinement technology for aluminum alloy.

针对揭示纳米晶种对Al合金α-Al枝晶尺寸与形貌的影响规律与机制所面临的关键科学问题，揭示出非晶加入熔体中纳米晶种形成的热力学和动力学规律与机制；纳米晶种对α-Al枝晶细化及形貌演化的动力学影响规律与机制；熔体中原位纳米晶种的稳定性及其对孕育衰退的影响规律与机制；非晶合金细化ɑ-Al枝晶尺寸、形貌对铝合金的室温、高温强韧性和蠕变行为的影响规律与作用机制。建立α-Al枝晶尺寸、形貌与室温、高温拉伸性能和蠕变行为的关系；通过原位晶化形成纳米晶种控制凝固组织和服役性能；提出细化α-Al枝晶的非晶设计准则。为揭示和丰富纳米尺寸晶种细化铝合金理论，拓展非晶合金的应用以及为开发新型先进的低成本、高效的铝合金细化剂和细化新技术奠定理论基础。

本研究以纳米颗粒强化调控-新的组织构型（晶粒细化、增强相尺寸、数量、分布调控）构建-性能优化为主线，实现铝合金组织细化、增强相晶内和晶界强化、高的组织高温稳定性调控为研究核心，针对揭示纳米颗粒对Al合金α-Al枝晶尺寸与形貌的影响规律与机制所面临的关键科学问题和研究难点，揭示了纳米颗粒对铝合金组织细化、初生α-Al相和析出相生长动力学的影响规律和作用机制，指导开发了新型高效纳米颗粒强化剂；揭示了纳米颗粒结构、形貌、高温稳定性对铝合金强化衰退和遗传性的影响规律与机制，优化强化技术和工艺；揭示了纳米颗粒强化铝合金的室温、高温及蠕变变形行为，揭示了室温、高温强韧化机制。汽车和高速列车用铝合金的纳米颗粒强化剂及强化技术是一项创新性的研究工作。本研究正契合智能制造和中国创造的科技发展潮流和国家导向，具有巨大的市场价值和应用前景。为高性能铝合金结构材料智能制造奠定强化技术基础。