Abstract: A solid state bonding process of malleable metals employing the isothermal solidification of a liquid interface to overcome bonding problems inherent in certain material combinations especially when subjected to high annealing temperatures. The technique employs the use of a solid metal interliner clad between the two components to be bonded which has a lower melting point than the adjacent components, is diffusible into either one or both of the adjacent components and maintains ductility after alloying with the adjacent components. The composite material is then heat treated above the melting point of the interliner causing momentary liquifying of the interliner, diffusing the liquid metal into either one or both of the adjacent components thereby forming a progressively higher melting point alloy and subsequent isothermal solidification of the high melting alloy to securely bond the two components together.