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 i n joints with excellent reliability and also shear strengths as high as tho se 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 solidificatio n to take place, this new method relies on the diffusion of solute in the l iquid phase. A precise analytical solution is proposed which is capable of predicting bonding times and bond line displacements when TLP diffusion bon ding under a temperature gradient. Based on a mass balance approach, a simp ler solution for predicting the bond line displacements and the bonding tim es is also suggested. The proposed model was verified experimentally for th e bonding of pure aluminium using a copper interlayer. The approach describ ed also has the potential to model conventional TLP diffusion bonding. (C) 1999 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights r eserved.