Study On Process And Mechanism Of TLP Bonded IC10Single Crystal And GH3039Superalloys

Aiming at the demand of connection between IC10single crystal and GH3039superalloy, in this paper the welding experiment was carried out by using transient liquidphase (TLP) diffusion bonding technology, with BNi2and five kinds of self-designedsolders as interlayers. Joint microstructure, mechanical properties and distribution ofmicrohardness were investigated. Based on the experimental study, the formation processof TLP bonded joint interface and the dissymmetry of dissimilar materials TLP diffusionbonding process were conducted.When using BNi2as an interlayer, after TLP diffusion bonding, diffusion zone (DZ)adjacent to IC10comprised of borides and silicide, while DZ adjacent to GH3039comprised of borides without silicide. Isothermal solidification zone (ISZ) comprised ofCr-rich Ni-based solid solution and Al4Ni15Ta sometimes. Eutectic zone (EZ) comprisedof Ni-based solid solution, borides and silicide. It is found that improving the holdingtime could help to achieve a joint without eutectic solidification product along the jointcenterline region, while improving the welding temperature could not always help tocomplete isothermal solidification, because though higher temperature can promote thediffusion of melting point depressant (MPD) elements, but it can also decrease theisothermal solidification rate. Because of the difference of the solute atoms diffusionspeeds and the metallurgical reactions between interlayer and base metals, thedissymmetry exists in dissimilar materials TLP diffusion bonding process. There was abig difference on microhardness between single crystal IC10and GH3039superalloy.After TLP diffusion bonding, EZ and DZ which had many precipitations were the mainzones that resulted in the uneven transition of microhardness across the joint. At theparameter of1200℃/2h, the distribution of microhardness across the joint was even, thushelping to improve the mechanical properties of the joint.When using five kinds of self-designed solders as interlayers, it is found that theeffect of depressing the melting point of the interlayer by element B was better than Si.Moderate content of B will help to forming a fine joint. To decrease the content of Si willcontribute to reduce the precipitations.The kinetics study of TLP diffusion bonding was reviewed. The dissymmetry in theTLP diffusion bonding process of dissimilar materials could result in the connectioninterface shifting to one of the base metal. The dissymmetry in the stage of isothermalsolidification was mathematical modeled. Computational formula of the offset frominterface to base metal was obtained. It was found that element B played a dominant rolein the dissymmetry.