Research On The Pre-diffusion Roll Bonding Technology Of Al/Ti Clad Sheet And Its Microstructure And Properties

In order to meet the needs of social development,laminated metal composite sheets have become the focus of research since its excellent properties.Al/Ti clad plate is characterized with specific strength,corrosion resistance and low density thus can be utilized in aerospace and medical applications.It always one of the difficult issues about improving the mechanical properties by control its microstructure and interfacial structure.Therefore,laminated Al/Ti clad plate with industrial purity titanium TA2 and commercial purity aluminum 1060 had been fabricated through add novel technique of cold rolling and pre-diffusion based on traditional rolling process and relationship between cold rolling add pre-diffusion,accumulative rolling bonding,annealing treatment and the properties,structure were investigated in this paper.The mechanical properties of Al/Ti composite sheets were tested by tensile test,microstructure and interfacial structure were characterized by SEM(Scanning Electron Microscopy),XRD(X-ray Diffraction),EDS(Energy-dispersive Spectroscopy)and EBSD(Electron Backscattered Diffraction).The strength of the Al/Ti clad plate fabricated by 450?,500?pre-diffusion reaches242MPa,257MPa,respectively,which are significantly higher than the 236MPa of conventional process;but 550?pre-diffusion only reaches 242MPa,which is lower than conventional process.Compared with conventional process,450?,500?pre-diffusion show an excellent Al/Ti interfacial bonding and interfacial necking decreased.Fragmented Al₃Ti phase is detected along the Al/Ti bonding interface of 550?pre-diffusion,which is attributed to the nucleation of crack and reduces the strength.Thickness of diffusion layer increase with the increased of pre-diffusion temperature and are higher than conventional process.The grains of Al layer of Al/Ti composite sheets prepared by pre-diffusion are markedly elongated but not parallel to RD.Lamellar twin structure can be observed in the Ti layer.The strength and ductility of Al/Ti clad plate prepared by 550?pre-diffusion are the best and texture of Al layer transformed to recrystallization texture and the different degrees of recovery and recrystallization occurred in Ti layer among of them after annealing.The strength and interfacial necking of Al/Ti composite sheets are increase after accumulative rolling bonding.The properties of six-layer clad plate by 550?pre-diffusion is higher than conventional process;rotated cube is mainly observed in the Al-outside,while the Al-inside is dominated by Goss cube;the grain size of Al layer increased and the maximum degree of recrystallization exceed 90%of Ti layer after annealing.Thickness of intermetallic compound increase as annealing times increased,it exhibits a parabolic law during annealing time from 1h to 20 h,then transform to linear behavior when annealing treatment exceed 20h.The growth of Al₃Ti layer occurs mainly towards Ti/Al₃Ti interface side.XRD shows Al is detected on the Ti-side but Ti is not found on the Al-side after peeled.