text: Transient liquid phase diffusion bonding is a process that differs from diffusion bonding.  In transient liquid phase diffusion bonding, an element or alloy with a lower melting point in an interlayer diffuses into the lattice and grain boundaries of the substrates at the bonding temperature.  Solid state diffusional processes lead to a change of composition at the bond interface and the dissimilar interlayer melts at a lower temperature than the parent materials.  Thus, a thin layer of liquid spreads along the interface to form a joint at a lower temperature than the melting point of either of the parent materials.  This method differs from brazing in that it is "isothermally solidifying".  While holding the temperature above the filler metal melting point, interdiffusion shifts the composition away from eutectic, so solidification occurs at the process temperature.  If sufficient interdiffusion occurs, the joint will remain solid and strong well above the original melt process temperature.  This is why it is termed "transient liquid phase."  The liquid solidifies before cooling.