水域环境多场耦合大块非晶合金塑性变形行为及断裂机理研究

Bulk metallic glasses (BMGs) would serve as engineering structural materials in the aquatic environment, due to their unique properties, including ultrahigh strength, hardness and corrosion resistance. Service liquid environment and its flow rate, temperature, corrosion and load are the key reasons to cause the crack initiation, expansion, leading to the final fracture and fatigue failure of the structural materials. Considering the complexity of the service environment as well as combining with the aqueous environment, especially the marine environment, the project would carry out the research on the plastic deformation behavior and fracture mechanism of BMGs under multi-field coupling operation from the water medium and its flow rate, temperature and strain rate. Through the characterizations of the structure, initiation and expansion of shear bands, stress transfer, crack propagation and fracture mode in deformed BMGs, and the investigations of evolution regularity of the structure, shear bands, free volume and fracture behavior during the deformation and fracture processes, the plastic deformation and fracture mechanism of bulk amorphous alloys in the aqueous environmental could be obtained. The proposal of this project can not only broaden the research field of BMGs, but also enrich and perfect the deformation and fracture theory, has important scientific significance, as well as important guiding value to promote the engineering applications of BMGs.

大块非晶合金具有极高的强度、硬度及耐腐蚀性，将成为工程结构材料在水域环境中服役。服役环境液体介质及其流速、温度、腐蚀以及载荷等都是造成结构材料裂纹萌生、扩展，导致最终断裂和疲劳破坏的关键原因。本项目综合考虑服役环境复杂性，结合水域环境，重点是海洋环境，开展大块非晶合金在水域介质及其流速、温度与应变速率等多场耦合作用下塑性变形行为及断裂机理研究，通过对变形后非晶试样组织结构、剪切带萌生及扩展、应力传递、裂纹扩展及断裂模式等进行表征，考察变形及断裂过程中组织结构、剪切带、自由体积及断裂行为的演变规律，获得大块非晶合金在水域环境介质中的塑性变形及断裂机理。本项目的开展，不仅可拓宽大块非晶合金的研究领域，而且还能丰富和完善其变形及断裂理论，因此，具有重要的科学意义，对促进大块非晶合金的工程应用具有重要的指导价值。

大块非晶合金具有极高的强度、硬度及耐腐蚀性，将成为工程结构材料在水域环境中服役。服役环境液体介质及其流速、温度、腐蚀以及载荷等都是造成结构材料裂纹萌生、扩展，导致最终断裂和疲劳破坏的关键原因。本项目综合考虑服役环境复杂性，结合水域环境，重点是海洋环境，开展大块非晶合金在水域介质及其流速、温度与应变速率等多场耦合作用下塑性变形行为及断裂机理研究。项目从大块非晶合金流变应力及断裂应力对温度高度敏感出发，研究介质温度和应变速率对流变应力及断裂应力的影响规律，重点是热应力对合金表观剪切带萌生与扩展及表观微裂纹累积和传递方式的影响规律，探索基体组织或结构在温度场中承载时弛豫机制对变形及断裂的作用机理，特别是对超大塑性大块非晶合金的塑性变形及断裂行为的作用机制。研究表明，非晶合金变形及断裂方式出现显著差异，相同载荷及应变速率下，随着温度升高，合金变形及断裂方式由脆性断裂向塑性剪切变形过渡；在玻璃转变温度以下，硬度随温度和压力升高而增大，载荷位移曲线上锯齿状特性及形貌上剪切带数量随温度升高显著减少，而应力波动范围及剪切带滑移间隔显著增加。在对大块非晶合金在水域介质及其流速场中变形及断裂过程的微观力学特性研究中，进一步深入考察介质流速率引起冲击应力及摩擦应力与承载作用下的合金基体应力，尤其是表观剪切应力和断裂应力的相互关系，探索介质流形成的扭转应力对非晶合金塑性变形及断裂行为的影响，特别是变形时表观剪切带的萌生与扩展及断裂时表观裂纹的累积与传递的影响。项目发表标准基金编号论文6篇，其中SCI收录4篇，EI收录5篇，ESCI收录1篇，获授权专利2项，其中发明专利1项，实用新型专利1项，取得了建设性研究成果。本项目的开展，不仅可拓宽大块非晶合金的研究领域，而且还能丰富和完善其变形及断裂理论，因此，具有重要的科学意义，对促进大块非晶合金的工程应用具有重要的指导价值。