The role of interlayers in diffusion bonded joints metal-matrix composites

Solid state bonded joints in a particulate metal-matrix composite containing 17 vol% SiC in Al-Li 8090 alloy had planar bond interfaces with particle-particle (P-P) interfaces and particle-matrix (P-M) interfaces aligned in and parallel to the bond interface. The insertion of a matrix interlayer into the MMC-MMC bond interface changed the type of particle interface and interface area fractions in the two new bond planes created. In these P-P interfaces became P-M interfaces and the P-M area fraction either increased or fell to zero depending on the particle symmetry with respect to the bond plane. The implications for the mechanical properties of diffusion bonded joints in MMCs are discussed. 8 refs.