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Aluminium austenitic stainless steel joints find application in cryogenic engines, spacecrafts and automobiles. This dissimilar material combination is unweldable by conventional fusion welding due to a tendency for brittle intermetallic formation. Solid state welding processes such as friction welding are reported to be employed in such situations. This paper deals with continuous drive friction welding of AA6061 Al alloy to AISI 304 austenitic stainless steel. Direct welding of this combination resulted in brittle joints with 0u bend angle due to the formation of Fe 2 Al 5 . To alleviate this problem welding was carried out by incorporating Cu, Ni and Ag as diffusion barrier interlayers. The interlayer was incorporated by electroplating. Welds with Cu and Ni interlayer were also brittle due to the presence of CuAl 2 and NiAl 3 . Ag acted as an effective diffusion barrier for Fe avoiding the formation of Fe 2 Al 5 . Therefore welds with Ag interlayer were stronger and ductile and could be bent to an angle of 100u.

Various pyrazole‐based P,N (2a–c) and N,N (3a–b) ligands have been synthesized. Using representative ligands, NiII, CoII, CuII, and CuI complexes have been prepared and structurally characterized by crystallography. During complexation of CoII and CuII salts, the phosphane part of the P,N ligand oxidized to phosphane oxide. For N,N donor ligands, a dimeric chloro‐bridged NiII complex was obtained. NiII complex 4 is an active catalyst for ethylene oligomerization. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)