(1. 中南大学 粉末冶金国家重点实验室，长沙410083；
2. 中南大学 材料科学与工程学院，长沙410083；
3. 中南大学 湘雅医院 肝胆胰外科，长沙410008；
4. 浙江工业大学 材料科学与工程学院，杭州310014)
摘 要: 仿贝壳结构或层状结构材料同时具有高的强度和韧性，是当前材料结构优化的重要设计模型之一。通过粉末冶金与热加工方法制备具有仿生结构特征的Ti-Ta金属-金属复合材料，并研究其动态力学行为。结果表明：仿生界面结构对Ti-Ta复合材料的变形行为具有重要影响，使材料的破坏行为表现为裂纹桥联和局部层裂，在力学变形上也表现出明显的应变速率强化、应变强化以及绝热软化特征。材料的屈服强度随着应变速率的提高而提高；在高应变速率下，随着变形量的增加，流变应力变化得较为平缓。采用改进的Johnson-Cook (J-C)本构模型能很好地描述Ti-Ta复合材料的动态行为，同时发现，Ti-Ta复合材料的应变速率强化指数C远低于纯Ta的，而略低于纯Ti的。
关键字: Ti-Ta金属-金属复合材料；应变速率强化；绝热软化；Johnson-Cook本构模型
（1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
2. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
3. Department of Hepatobiliary and Pancreatic Surgery, Xiangya Hospital, Central South University, Changsha 410008, China;
4. College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou 310014, China）
Abstract:Materials with shell-like or layered structure exhibit both high strength and toughness, which makes them become one of the important design models for material structure optimization. A Ti-Ta metal-metal composite with biomimic structure was prepared by powder metallurgy and thermal processing, and its dynamic behavior was studied. The results show that biomimic interface structure has an important influence on the deformation of the Ti-Ta composite, and the fracture behavior includes crack bridging and lamellar spallation. The metal-metal composite is subjected to the combined effects of strain rate strengthening, strain strengthening and adiabatic softening. Specifically, the yield strength of the composite increases with the increase of strain rate, and the flow stress changes more gently with the increase of deformation at high strain rate. The modified Johnson-Cook (J-C) constitutive model can well describe the dynamic behavior of Ti-Ta composite, and it is found that the strain rate strengthening index C of Ti-Ta composite is much lower than that of pure Ta and slightly lower than that of pure Ti.
Key words: Ti-Ta metal-metal composite; strain rate strengthening; adiabatic softening; Johnson-cook constitutive model
