抗菌高强韧铁基中熵合金结构功能一体化调控机理研究

防疫抗菌材料的结构功能一体化调控是该领域的关键科学问题，探索新型高强韧抗菌铁基中熵合金具有重要的社会经济效益。本项目设计fcc+hcp结构铁基中熵合金，通过添加与主元素混合焓为正值的抗菌元素，由相分离析出协同抗菌富集相；通过成分优化降低层错能同时强化奥氏体，由应力诱发产生的hcp(ε)马氏体相变增强增韧并促进加工硬化率；由热诱发和应力诱发hcp(ε)马氏体在高应力区的TWIP效应，提供稳定的加工硬化；由热处理产生Shockley不全位错逆运动和ε马氏体内层错重新形核，实现组织再生与再利用。本项目将优化出高强高韧且抗菌耐蚀的铁基中熵合金的成分范围，分析成分调控对层错能和相形成规律的影响，揭示亚稳相变路径与形变孪生机制，建立不同加工硬化阶段的Hall-Petch关系，并由可逆相变及孪晶内耗行为、位错/孪晶密度和温度波动间的关系揭示变形与再生机制，阐明协同抗菌机理并建立合金的热加工制度。

The integrated control of mechanical and functional properties of the antiepidemic and antibacterial materials is a key scientific issue in this field. It will bring remarkable social and economic benefits by exploring a new type of antibacterial high-performance structural Fe-based medium entropy alloy with integrated functional properties. This project designs a novel fcc+hcp Fe-based medium entropy alloy. By adding the antibacterial elements, which exhibit positive mixing enthalpy with main elements in the medium entropy alloy, induces the phase separation to precipitate synergistic antimicrobial fcc2 phase, and thus improves the broad-spectrum antibacterial property and durability. Via composition optimization, the stacking fault energy is reduced and the austenite phase is strengthened. And the stress induced hcp(ε) martensitic transformation not only enhance both the strength and toughness, but also promote work hardening rates. In addition, the TWIP effect of both heat and stress-induced hcp(ε) martensite in the high stress area facilitates the stable work hardening. And the microstructure regeneration and reuse can be realized by the heat treatment induced reverse movements of Shockley incomplete dislocation and the renucleation of stacking fault in ε-martensite. This project will study the effects of component control on the stacking fault energy and phase formations. And the metastable transformation path and deformation twin mechanism will be investigated. Based on these, the Hall-Petch relationship in different work hardening stages will be established. Furthermore, the deformation and regeneration will be understood by the internal friction behavior of reversible phase transformation and twinning, and the relationship between the density of dislocation /twin and the temperature fluctuation. And the mechanism of synergetic antibacterial will be revealed and finally, the heat treatment regimes of the novel medium entropy alloy will be established.