Research On Deformation Texture Of Cu/Ti Composites Processed By Accumulative Rolling Bonding

Compared with other SPD technologies,accumulative roll bonding process shows outstanding advantages,such as simple equipments,large sample size,continuous industrial production of ultra-fine crystal sheets.Accumulative roll bonding process is the only promising technology which can realize large-scale industrial produce of large volume ultra-fine crystal materials continuously.In this thesis,the Cu/Ti composites which acted as the model materials were fabricated by accumulative roll bonding,and the deformation texture of the layered composites composed of the face-centered cubic metal and close-packed hexagonal metal was studied.The microstructures of the Cu/Ti composite were investigated by means of metallographic microscope.The mechanical properties of the Cu/Ti composite were investigated by the hardness test and uniaxial tensile test.The distribution and evolution of the texture of the Cu/Ti composites were analyzed using X-ray diffraction technology.This study is the guidance for the Cu/Ti composites regarding mechanical properties,texture evolution and the influence of hetero-interface on the texture distribution of single-layer metals.The observation of the microscope shows that with the increasing number of ARB cycles,noticeable bending occurs,i.e.,significant necking and fracture occurs in titanium layers in which thickness is unevenly distributed along rolling direction.In addition,shear bands appear in the titanium layer where the thickness is reduced non-uniformly.The copper layers in the composites remain continuous after different ARB cycles.The results of the mechanical property testing show that with the increasing number of ARB cycles,the values of the yield strength and tensile strength of the Cu/Ti composites keep increasing and are located between the values of two pure metals,and the plastic elongation decreases gradually.After the fourth ARB cycle,the composite still retains a certain plastic deformation capacity,i.e.,the maximum elongation can reach more than 15%.The analysis of the XRD texture determination shows that during the two processes of accumulative roll bonding and cold rolling of the Cu/Ti composite,the texture of the copper layer is mainly the brass-type,while in the titanium layer there is a significant?1120}<1010>texture in addition to the {0001} basal double-peak texture.The deformation texture type is different from the typical rolling texture of the pure copper or titanium.The reason for the appearance of the abnormal texture is attributed to the fact that the stress accumulation at the hetero-interface in the multi-layer composites triggers the shear band activation within the component metals.