Solid phase diffusion bonding of Ti₂AlNb alloy and titanium matrix composites at low temperature

Abstract

The Ti2AlNb alloy and the titanium matrix composites can be joined by direct solid phase diffusion, but the high diffusion temperature causes the base metal to undergo a phase transition, even the joint properties were therefore deteriorated. A method for optimizing the properties of solid phase diffusion joints of Ti2AlNb alloy and Ti matrix composites was proposed by using Ti foil intermediate layer. The results show that after adding 30 μm Ti foil intermediate layer, the diffusion bonding temperature reduces from 950 ℃ to 850 ℃, the deformation rate reduces from 5% to 1.7%, and the decreasing of diffusion bonding temperature can effectively change the structure of the joint interface. The typical interface is Ti2AlNb/B2 phase/α+β dual phase structure/Ti matrix composite, in which the strength of the joint increases by the formation of α+β dual phase structure at the joint interface.When the optimum diffusion bonding parameter is 850 ℃/60 min/5 MPa, the shear strength reaches a maximum value of 399 MPa. The diffusion bonding of Ti2AlNb and Ti based composite at low temperature is realized.

Keywords

• ti₂alnb alloy
• titanium matrix composite
• diffusion bonding
• interfacial microstructure