Analytical modelling of transient liquid phase (TLP) diffusion bonding when a temperature gradient is imposed

Transient liquid phase (TLP) diffusion bonding with a temperature gradient across the bond region is the basis of a new bonding method which results in joints with excellent reliability and also shear strengths as high as those of the parent material (e.g. aluminium-based alloys and composites). In contrast to conventional TLP diffusion bonding where diffusion of solute in the solid phase is traditionally assumed to be necessary for solidification to take place, this new method relies on the diffusion of solute in the liquid phase. A precise analytical solution is proposed which is capable of predicting bonding times and bond line displacements when TLP diffusion bonding under a temperature gradient. Based on a mass balance approach, a simpler solution for predicting the bond line displacements and the bonding times is also suggested. The proposed model was verified experimentally for the bonding of pure aluminium using a copper interlayer. The approach described also has the potential to model conventional TLP diffusion bonding. (C) 1999 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.