The nucleation and growth of diamond on ultra-thin Cr/Al and Ti/Al interlayered stainless steel substrates were investigated. The metal interlayers were produced by ion beam sputtering deposition and consisted of an outer layer of 20nm Cr or Ti and an inner layer of 30nm Al, respectively. During the microwave plasma-enhanced chemical vapor deposition process, the inner Al diffuses into steel surface and forms Fe-Al compounds, while the outer Cr or Ti is carburized and transformed into corresponding carbides. These two ultra-thin dual metal interlayers are effective in suppressing the graphite soot formation on steel surfaces. Nevertheless, continuous diamond thin film is difficult to be obtained due to severe buckling and fragmentation deformation induced by residual stress. (C) 2010 Elsevier B.V. All rights reserved.