STUDY OF PULSED HIGH-ENERGY DENSITY PLASMA-MODIFIED 0.45-PERCENT-C STEEL

The hardness of the surface of 0.45%C steel is improved by about six t imes after the surface is modified by pulsed high-energy density plasm a (PHEDP) composed of particles of titanium and nitrogen. A layer of t hin film about 1 mu m thick is formed on the treated surface and the m icrostructure of the film is examined by transmission electron microsc opy, which shows that the film comprises TIN, Ti2N(alpha), Ti2N(beta) and FeTi phases. In PHEDP surface modification, the process of ion imp lant combined with melting and rapid quenching contributes to the form ation of the polyphase film on the surface of 0.45%C steel, especially to the formation of nanometer particles and the metastable phase of T i2N(alpha) in the film. The structure polyphase film is the main reaso n for the hardness improvement of the surface of 0.45%C steel. The cha racteristics of Ti2N(alpha) and Ti2N(beta) phases are discussed in pap er. (C) 1998 Elsevier Science B.V. All rights reserved.