(1. 中南大學(xué) 粉末冶金國家重點(diǎn)實(shí)驗(yàn)室，長沙410083；
2. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙410083；
3. 中南大學(xué) 湘雅醫(yī)院 肝膽胰外科，長沙410008；
4. 浙江工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，杭州310014)
摘 要: 仿貝殼結(jié)構(gòu)或?qū)訝罱Y(jié)構(gòu)材料同時(shí)具有高的強(qiáng)度和韌性，是當(dāng)前材料結(jié)構(gòu)優(yōu)化的重要設(shè)計(jì)模型之一。通過粉末冶金與熱加工方法制備具有仿生結(jié)構(gòu)特征的Ti-Ta金屬-金屬復(fù)合材料，并研究其動(dòng)態(tài)力學(xué)行為。結(jié)果表明：仿生界面結(jié)構(gòu)對(duì)Ti-Ta復(fù)合材料的變形行為具有重要影響，使材料的破壞行為表現(xiàn)為裂紋橋聯(lián)和局部層裂，在力學(xué)變形上也表現(xiàn)出明顯的應(yīng)變速率強(qiáng)化、應(yīng)變強(qiáng)化以及絕熱軟化特征。材料的屈服強(qiáng)度隨著應(yīng)變速率的提高而提高；在高應(yīng)變速率下，隨著變形量的增加，流變應(yīng)力變化得較為平緩。采用改進(jìn)的Johnson-Cook (J-C)本構(gòu)模型能很好地描述Ti-Ta復(fù)合材料的動(dòng)態(tài)行為，同時(shí)發(fā)現(xiàn)，Ti-Ta復(fù)合材料的應(yīng)變速率強(qiáng)化指數(shù)C遠(yuǎn)低于純Ta的，而略低于純Ti的。
關(guān)鍵字: Ti-Ta金屬-金屬復(fù)合材料；應(yīng)變速率強(qiáng)化；絕熱軟化；Johnson-Cook本構(gòu)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
