Joining of Al2O3p/Al composites by transient liquid phase (TLP) bonding and a novel process of active-transient liquid phase (A-TLP) bonding

Transient liquid phase (TLP) bonding of Al2O3p/Al was performed using Cu, Al–Cu and Cu–Ti system interlayers. The reinforcement/metal (R/M) interfaces are classified into two types: primary R/M interfaces (as-prepared) and secondary R/M interfaces (after bonding). The shear strength of TLP bonded joint using Cu foil was restricted by the weakening of the secondary R/M interfaces, notch around faying surfaces and particulate segregation. Active-TLP (A-TLP) bonding using an interlayer containing both melting point depressant (MPD) and active element which can react with ceramic reinforcement is proposed to improve the wettability between the secondary R/M interfaces. Its feasibility using Cu–Ti foil was demonstrated: the adhesives formation and disrupted particulates were observed on the joint fracture surfaces; the fracture of the joint partially propagated into sound parent composite. For Al–Cu interlayer, although the joints without particulate segregation could be obtained, unbonded regions and voids were observed. A suitable interlayer composition design route is proposed.