Study On The Process And Mechanism Of The Diffusion Bonding Between Ti₂AlNb And Ti Matrix Composite

Ti2AlNb alloy has excellent properties such as the high tensile strength and fatigue strength of high temperature,better room temperature fracture toughness and crack growth resistance.It has become a hot topic in research of aerospace materials.However,the presence of Nb makes it has a higher density than other TiAl-based alloys.Combining it with Ti matrix composites based on TA15 can reduce the weight of structural parts and broaden the application of Ti2AlNb.In this paper,Ti2AlNb and Ti matrix composites were bonded by solid diffusion bonding directly and with interlayers.Exploring the best process parameters for the connection between the two.It is expected that selecting the appropriate intermediate layer can reduce the connection process parameters while improving the performance of the joint and reducing the deformation of the joint,then analyze the interface connection mechanism.Ti2AlNb and Ti matrix composites were bonded by diffusion bonding directly,phase transition of the base metal was analyzed to determine the connection process parameters for the range of 850-1050?/15-90min/3-10MPa.The typical interface structure is Ti2AlNb/B2+0+TiB/O+?-Ti+P-Ti+TiB/Ti matrix composites,The best process parameter is 950?/60min/5-7MPa,the maximum shear strength reaches 495 MPa under this process parameter,the fracture mode is ductile fracture.In the process parameters of 950?/60min/3-5MPa,the deformation rate of welded joints can be controlled below 3%.Ti2AlNb and Ti matrix composites were bonded by diffusion bonding with interlayers.After joining the Ti foil interlayer,the typical interface structure is Ti2AlNb/B2-rich/?+?-phase/Ti matrix composite.The best process parameter is 850?/60min/5MPa,the maximum shear strength reaches 399MPa under this process parameter,the fracture mode is ductile fracture.Exploring the mechanism of the Ti foil interlayer can lower the connection temperature to 850?.In the process parameters of 850?/60min/5MPa,the deformation rate of welded joints can be controlled below 2%.Diffusion bonding of two base metals after magnetron sputtering of metal film on Ti matrix composites,characterization of the properties of magnetron sputtered metal films,The typical joint structure is Ti2AlNb/B2+0/Ti matrix composites after diffusion bonding of Ti film by magnetron sputtering,The typical joint structure is Ti2AlNb/B2/0+?-Ti+B2+a-Ti/Ti matrix composites after diffusion bonding of Nb film by magnetron sputtering.Both can be well connected at 850?/60min/5MPa process parameters,exploring the diffusion mechanism of reducing the diffusion temperature to 850?after magnetron sputtering of metal film.The two base metal were bonded by diffusion bonding with hydrogen TC4 interlayers,after adding hydrogen TC4 interlayer,the connection temperature reduced to750?,the typical diffusion interface structure is Ti2AlNb/O+?-Ti+B2+?-Ti/Hydrogen TC4/Ti matrix composites,exploring the effect of different hydrogen content on interface morphology under the same process parameters,analysis the diffusion mechanism of hydrogen promotes atomic diffusion and significantly reduces the diffusion temperature.