Isothermal solidification behavior during the transient liquid phase bonding process of nickel using binary filler metals

Transient liquid phase (TLP) bonding process of Ni using Ni-11.0 mass%P bin ary filler metal was simulated by using a mathematical model based on diffu sion analysis. In the model, diffusion-controlled transformation was assume d, and the base metal dissolution in the early stage and the subsequent iso thermal solidification stage of the TLP bonding process were simulated. The calculated width of me eutectic structure at the bonding region agreed wel l with the experimental result and showed the validity of the model, in ord er to obtain the condition to reduce isothermal solidification time, the ef fect of factors, such as the width of filler metal, diffusivity of solute e lement in Ni and partition coefficient of element, were investigated by num erical simulation. The simulation showed that isothermal solidification lim e remarkably decreases with increasing partition coefficient of solute elem ent. In order to confirm the numerical prediction, the TLP bonding experime nt of Nj using Cu filler metal was carried out (the partition coefficient o f Cu in Ni is close to unity). The experimental result showed that Cu fille r metal remarkably shortened the isothermal solidification time and showed the validity of the prediction.