Study On Diffusion Welding Interface Of Ti/Al

Titanium and titanium alloy have many good characteristics, such as high melting point, good corrosion resistance, small linear expansion coefficient, small elastic modulus and so on, which make them widely used in industry. Titanium alloy has been applied in important bearing components, but the problem of its connection is the key to restrict its application. Aluminum and aluminum alloy have many advantages, such as high strength, small density, good plasticity, good corrosion resistance, conductive thermal conductivity, easy to machining, light weight with low price and so on, which make them widely used in automobile, shipbuilding, electrical, chemical and national defense industry, etc. Because of some special properties of the titanium alloy and aluminum alloy, Ti/Al composite component has been used as a new type of structural materials in the field of aerospace and chemical electrolysis industrial applications. The structure of Ti/Al composite has good stability, high temperature resistance and insulation performance, which can play a maximum potential characteristics of the two materials. Therefore, it is necessary to weld titanium and aluminum. But the traditional fusion welding will bring some inevitable defects during welding these two kinds of materials, the vacuum diffusion welding which adopts in this paper can effectively avoid melting welding defects.This topic selects industrial pure titanium and pure aluminum foil as the raw materials, making TA2-aluminum-TA2 sample by using the method of vacuum diffusion welding. After that interface, element distribution, fracture morphology and phase of fracture morphology analyze in using scanning electron microscope, energy spectrometer and X-ray diffraction. The values of microhardness and shear strength can be acquired by microhardness tester and shear test. At the same time the effect of the different process parameters on element distribution the microstructure and mechanical properties has also been analyzed.Experimental results show that specimen shear fracture morphology obviously changes along with the rise of temperature as the temperature changing between 550℃ and 700℃, which changing from dimple to cleavage shape; the shear strength of the sample reaches the maximum whose value is 81 MPa when the temperature reaches 550℃ and the thermal insulation reaches 240min; when the temperature reaches 600℃, the shear strength of specimens changes as the prolongation of holding time which increases first then decreases, and reaches the maximum when the holding time reaches 120min; when the temperature reaches 650℃, the shear strength gradually reduces with the prolongation of holding time, and reaches the minimum value which is 28MPa; when the temperature reaches 700℃, the shear strength changes as the prolongation of holding time and increases stably; when the temperature reaches 550℃ and 600℃, the microhardness of each sample near the interface of titanium/aluminum increases obviously, and the peak value is greater than the value of the substrate of titanium and aluminum; the microhardness of the specimens when the temperature reaches 700℃ by the aluminum side, is higher than the value of original aluminum; according to the result of the XRD analysis of fracture on both sides of the specimens, the location facture is the interface of titanium/aluminum or aluminum substrate transition layer.