TRANSIENT LIQUID-PHASE BONDING OF ALUMINA AND METAL-MATRIX COMPOSITE BASE MATERIALS

Transient liquid-phase (TLP) bonding of aluminium-based metal matrix c omposite (MMC) and Al2O3 ceramic materials has been investigated, part icularly the relationship between particle segregation, copper interla yer thickness, holding time and joint shear strength properties. The l ong completion time and the slow rate of movement of the solid-liquid interface during MMC/Al2O3 bonding markedly increased the likelihood o f forming a particle-segregated layer at the dissimilar joint interfac e. Preferential failure occurred through the particle-segregated layer in dissimilar joints produced using 20 and 30 mu m thick copper foils and long holding times (greater than or equal to 20 min). When the pa rticle-segregated layer was very thin (<10 mu m), joint failure was de termined by the residual stress distribution in the Al2O3/MMC joints, not by preferential fracture through the particle-segregated layer loc ated at the bondline. Satisfactory shear strength properties were obta ined when a thin (5 mu m thick) copper foil was used during TLP bondin g at 853 K.