Conference Reports
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Conference Shows Progress in Ion Beam Modification of Metals Many people associate the ion beam modification of materials surfaces primarily with the semiconductor industry, where such modification, particularly implantation of dopants, has seen commercial application. For well over two decades, however, those working with energetic beams of ions of all the elements have also investigated their effects on metals. Researchers associated with this work met at the eighth in a series of international conferences on the surface modification of metals by ion beams (SMMIB '93) during the week of September 13, 1993, in Kanazawa, Japan. The conference comprised about 45 talks—nearly half of which were invited lectures—and more than 120 posters presented by researchers from the United States, China, Japan, and several European countries. The topic covered in most detail, and one that has become the traditional subject of such conferences, was the implantation of nitrogen into ferrous alloys, including typical steels. This treatment mainly improves tribological properties, a result which was a purely empirical one in the "early days." The 1993 conference demonstrated that a great deal more scientific understanding of the underlying processes has been gained, and a far wider variety of implantation conditions and property enhancements is now being pursued. The physical phenomena altered by ion beams, usually for the better, included (in addition to friction and wear properties) corrosion in various environments, adhesion of thin films, optical properties, crystal structures and metastable phases, impurity diffusion, trapping and redistribution, diffusion barriers, and even micromachining. In addition to direct ion implantation, ion beam mixing of thin-film layers, ion beam stitching or knitting for adhesion of thin films, ion-beam-assisted deposition, and ion beam modification of structures, including amorphization, were described. Other papers addressed the implantation of carbon with nitrogen or alone, and the formation of carbides and carbonitrides. Many variations of techniques were described: implantation of multiple ions sequentially or simultaneously, implantation at a sequence of different temperatures, implantation through sacrificial layers in order to reduce the effect of sputtering on dose limitation, and varia42
tion of the energies and angles of incidence in order to affect the texture of ion-beam-assisted deposited films. Several beneficial ion implantation applications have been demonstrated in the past, perhaps the most well known being ion implantation on the cutting edges of razor blades. Ion implantation has also been successfully applied to nuclear cladding and to bearings in Naval helicopters, as well as to motor racing bearings, tool bits, and orthopedic implants, among other applications. Massive application of this technology in the marketplace has yet to occur, however. Presentations at the Kanazawa meeting showed that the facilities needed to demonstrate the efficacy of ion beam modification for com
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