The Interface Evolution And Performance Of The Ti/al Composite Materials Research

At present, hydrometallurgy and electrochemistry industry will do harm to the consumption of resources, energy and environment.Thus, to develop a new type of electrode material which will be used to replace the traditional electrode and have the characteristics such as good electrical conductivity, good performance,strong adaptability and low costs has a very important significance in the field to promote the progress of technology,energy consumption and environmental protection. The subject changes the matrix structure model of traditional electrode materials from the the composition of the internal structure of the matrix,uses solid-solid compound method of hot pressing diffusion welding for "sandwich type" structure Ti/Al electrode. Aluminum inner core as electrode conducting path plays an important part in reducing resistance and equalizing current distribution.but the outer metal titanium still keeps the electrochemical properties of "valve metal". Testing the Ti/Al laminates composite materials by using SEM,XRD, HRTEM,electrochemical performance and so on,and calculating by first-principle based on density functional theory,to discuss the interface evolut-ion mechanism and performance of Ti/Al laminates composite materials.The findings indicate that the interface formation of Ti/Al laminates composite materials is a reaction-diffusion process. In the technology conditions of this subject,the phase of interface is Al3Ti.The crystallogra-phic orientation between Al3Ti and Al (or Ti) could show certain relation-ship as follows:(111)Al‖(112)Al3Ti,(200)Al‖(200)Al3Ti,(101)Ti‖(112)Al3Ti and (101) Ti‖(004)Al3Ti.One of the most stable is Al(111)‖Al3Ti(112) and Ti(101)‖Al3Ti(004),respectively.The relationship between the interface thickness of Ti/Al composite materials and the holding time is the power function.The relationship between the interface thickness of Ti/Al composite materials and the welding temperature is the exponential function.The electrochemical performance of Ti/Al laminates composite electrodes are much better than traditional pure titanium electrode.The thickness of Ti and Al are respectively much thinner and thicker,the electrochemical performance of Ti/Al laminates composite electrodes are much better.The matrix current transmission mechanism of Ti/Al laminates composite electrodes is energy minimization rule.That is, the current longitudinally inflows by Al matrix firstly,horizontally transfers by Ti matrix, flows out titanium surface and the current flow into the electrolyte at last.By first-principles calculations calculated, this subject shows the band structure,density of states and charge distribution of AlTi3,AlTi,Al2Ti and Al3Ti.The formation enthalpy and binding energy of four kinds of Ti-Al intermetallic show certain relationship as follows:AlTi3<AlTi<Al2Ti<Al3Ti andAlTi3<AlTi<Al2Ti<Al3Ti, respectively. Consequently, Al3Ti is the first formation phase.AlTi3is the most stabile, AlTi second,Al2Ti third, Al3Ti last.