Effect of Heterogeneous Ti Layers on Mechanical Properties of Cu/Ti Laminated Sheets Prepared by Accumulative Roll Bonding

Abstract

Laminated metallic sheets have attracted public attention of all kinds due to its potentiality in new applications scenarios. [1] These sheets demonstrate splendid attributes of formalities and functionalities, like ameliorated strength, thermal stability, and the resistant feature to radiation impairment. Cu/Ti laminated sheets that combine the advantages of Ti and Cu have such merits as excellent yield strength (YS), elastic limit, electrical conductivity, ductility, and fatigue resistance. As a novel electrode material, it has developmental prospect in electrolytic extraction, electrochemical industry, current-carrying components, electromagnetic relays, and aerospace devices. [2,3] Up to date, Cu/Ti laminated sheets are usually cultivated by braze welding, [4] diffusion welding, [5] friction welding, [6] and explosive welding. [7] However, the high heat generated has downgraded its overall performance, which can easily cause the forming of unfavorably bonded brittle intermetallic compounds at the interface, thus limiting its application. [8] As the demand for multilayered metallic composites continues to emerge in the market, one of the most promising techniques, accumulative roll bonding (ARB), has been proposed by Saito et al. to produce laminated sheets with excellent interface bonding and better strength. [9,10] This technique can optimize the microstructure of composite foundation of the compensation for defects, with the assistance of huge accumulative strain. Besides, ARB has potential for industrialization due to its continuous procedures and high production rates. [11] In recent years, the ARB technique has been successfully adopted to process laminated sheets like Al/Cu, [12,13] Cu/Nb, [14,15] Ti/Al, [16] and Ni/Ti. [17] However, though the tensile strength of the composites increases as per the continuous ARB processes, the improvement in ductility is minimal. As a matter of fact, heat treatment is usually used to improve the comprehensive mechanical properties of the composites. But the intermetallic compounds produced in the process may reduce the strength of the composite. Recent studies potentiated that designing and fabricating metallic materials with heterogeneous structures can yield an excellent combination of high strength and good ductility. [18][19][20][21] Li et al. [22,23] conducted diffusion welding, cold rolling, and annealing to prepare copper/bronze laminates with better physical properties. They found that the grain size of the copper layer (%26.8 μm) was bigger in contrast to the bronze layer