Microstructure and Mechanical Properties of Multilayered Cu/Ti Composites Fabricated by Accumulative Roll Bonding

Abstract

Multilayered composites composed of pure copper and titanium (Cu/Ti) have been fabricated by accumulative roll bonding (ARB). The macroscopic lamellar structures, mechanical properties and microstructures of the composites are investigated. The results show that the Cu and Ti layers are bonded well during the ARB processing. With the increasing number of ARB cycles, Ti layers start to neck, fracture and even segregate within the Cu matrix, which is attributed to the activation of shear bands that cut through the multiple metal layers. At larger ARB cycles, the distribution of small fragmentations of Ti inside the Cu matrix is more homogeneous, which is attributed to the fact that the outer surfaces of the previously processed composite are placed in the interior of the subsequent ARB stack. Tensile testing at room temperature shows that the yield strength and the ultimate strength of the composites increased mildly with the increasing ARB cycles, while the uniform elongation of the composites is retained. Microhardness tests reveal that the increase of strength in the composites during ARB mainly results from the reinforcement of the Ti layers. The mechanical behaviors of the composites can be attributed to the effect of the mixed microstructures in the both constituent metals.

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

“…Meanwhile, the sample is simultaneously affected by the rolling pressure and friction, resulting in a shear force of approximately 45°, leading to the creation of shear bands. [ 10 ] During ARB cycles, the softer coarse‐grained Ti layer consumed most of the shear force, which made the composite maintain the layered structure. There are five different thicknesses of Ti layers in the ARB4 sample that averagely thicknesses from 23.22, 55.70, 90.80, 173.25, and 269.69 μm, corresponding with value from Ti‐0 to Ti‐4.…”

“…[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.…”

Forming limit diagrams and mechanical properties of AA1050/Ti CP2 multilayered composite produced by the accumulative roll bonding technique

“…25,27,42 Additionally, the Ti layer's discontinuity is also related to the formation of shear bands demonstrated by dashed lines (Figure 5(b)). 28 These shear bands originate from in-plane shear stress at the interface of the adjacent layers. The Al matrix acts as a transfer medium for the load to the Ti layer in the deformation process.…”

“…42 The simultaneous increase in UTS and decrease in elongation is a common paradox widely reported by other researchers. 28 Microhardness variations of the Al and Ti layer are illustrated separately in Figure 9, together with annealed samples. At the first ARB cycle, the microhardness of both phases gets a sharp rise from 25 and 145 to 52.64 and 205.26 VHN, respectively, for Al and Ti layers.…”

“…22 In addition to the research mentioned above, for metallic multilayered composites, which is the case for the present study, a significant number of works have been conducted during recent years, including Zn/Sn, 23 Cu/Ni, 24 Cu/Zn, 25 Al/Cu, 26 Al/Mg, 27 Cu/Ti. 28 It should be noted that the majority of researches have been focused on microstructure and mechanical properties. It is not only true about ARB but also about cold roll bonding processes (CRB).…”