Abstract: The fabrication of A199.5 pure aluminium-clad CuZn39Pbl leaded brass bars by multi-billet extrusion (MBE) process at elevated temperatures is investigated. The deformation behaviors of the composite, as well as the bonding between the inner (CuZn39Pbl ) and the outer (A199.5) materials, are studied. The diffusion features of the alloying elements of Cu, Zn and A1 across the interface are analyzed. The results indicate that the variation of extrusion force is consistent with the processes of filling of outer material into welding chamber, cladding of the outer material to core and extrusion of the clad rod. Evident diffusion of the alloying elements across the interface of the composite is confirmed, and diffusion layers with different structural contrast form as a result. The layer thickness increases with the extrusion temperature. The leaded brass core is clad homogeneously by pure aluminium along either longitudinal or cross section of the as-extruded composite rod, and excellent metallurgical welding is attained. The bonding strength of the composite interface is reduced when too low or too high extrusion temperatures are employed.

Key words: Composite materials, Diffusion Interface, Multi-billet extrusion