Property modification of structural materials by charged particle beams

Property modification of structural materials by charged particle beams

Vacuum News Conferences, courses and group activities Property Modification of Structural Materials by Charged Particle Beams The Second All-Union Co...

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Vacuum News

Conferences, courses and group activities Property Modification of Structural Materials by Charged Particle Beams The Second All-Union Conference on Property Modification of Structural Materials by Charged Particle Beams, organized by the Institute of Electrophysics, the Urals division of the USSR Academy of Sciences, was held at Sverdlovsk, 21-24 May 1991. The contributions to the conference were arranged within three sessions: (A) Charged particle beam sources for structural material modification ; (8) Physics of ion and electron beam effects on materials; and (C) Property modification of structural materials through charged particle beam treatment. The presentations included 45 plenary papers and nearly 200 posters with a total of 38, 66 and over 100 covering the topics of Sessions A, B and C, respectively. The conference was opened by academician G A Mesyats (Chairman of the Urals division of the USSR Academy of Sciences), followed by S P Bugaev reviewing the major developments in the field of beam technologies and charged particle sources, achieved at the Institute of High-current Electronics, Siberian division of the USSR Academy of Sciences. Session A had wide coverage of vacuum-arc and pulse-spacing sources as well as high-current electron and ion sources. A I Ryabchikov, in particular, devoted his paper to features and possibilities of vacuumarc sources and pulse-spacing implantation techniques based on the vacuum arc. The trend has been seen to enhance the mean beam current (up to IO-60 mA), develop multi-element ion fluxes with controlled beam energy and composition, and combine ion and plasma irradiation regimes. N V Pleshivtsev and his co-workers highlighted the problem of a small quantity production of superpowerful ion sources of hydrogen and helium (4-l 10 A, 5.6 MW, 1 O-80 keV, 0.01-l s). A number of presentations (by V I Perevodchikov and others) dealt with the perspectives of electron-beam devices, electron sources based on a plasma-filled diode, high-voltage electron accelerators (200-750 keV, up to 2.5 MeV) for structural material treatment and pulsed electron sources. Some poster contributions covered design considerations for glow discharge/cold hollow cathode ion sources (N V Gavrilov), lowpressure arc/cathode spot ion sources (Vu E Kreindel’ et a/), ion sources with an inverted plate magnetron geometry (A A Bashneyev) and high-frequency sources (N I Alinovsky). Interesting results were reported by M A Vinogradov and co-workers on the thin polymeric coating deposition process using a colloidal electrostatic source wherein a polymer solution was sprayed at an electric field strengh of 1 OS-10’ V mm’ to produce homogeneous/pm polymer (polymethylmetacrylate) films of high adhesion, as electrical insulators. This session (the contribution by N V Gavrilov el a/, in particular) focused on the industrial facility development for electron- and ionassisted treatment of parts and assemblies. A corpuscle-beam energy complex was described, producing electron and gas ion beams for use in electron-beam technology of the surface heat strengthening of steels and pig iron, for nitrides formation by nitrogen implantation in titanium, fatigue strength enhancement of high-temperature alloys, etc. An outline was given by V T Barchenko et al of a non-separated beam accelerator as an engineering module for material treatment by nitrogen and argon ions at an energy up to 60 keV and beam currents up to 1 mA. The accelerator can be used in processing lines for parts cleaning, nitriding, alloying, ion mixing and oxidation processes. The range of engineering complexes includes, apart from those for material treatment, ion beam-based diagnostics applications. The paper

by A L Bortnyansky et al presents an analyser scheme comprising an accelerator of hydrogen and helium ions with three channels for the accelerated-beam handling, which is provided with analysing equipment and automatic analysing control systems. The accelerator ensures production of ion beams at 0.5-2 MeV and a current of about 1 PA, enabling implementation of three nuclear microanalysis techniques (Rutherford backscattering, ion-induced X-ray, instantaneous nuclear radiation). Looking at the topics covered within Session A, one can note the trend in the developments towards commercial and semi-commercial plants and layouts with a wide range of features and operating parameters, and versatility manifested in that the above techniques fino application not only in conventional fields (such as thermonuclear synthesis, microelectronics and electronics, space materials science, electrophysics, instrument making), but also for surface property modification of metals in mechanical engineering, agricultural machinery and furniture industries, toolmaking, aircraft industry, shipbuilding and light industry, as well as for treating structural materials, cutting tools, pig iron, kapron (nylon), chipwood boards, alloys, polymers and glass. Session B contributions were devoted to fundamental aspects of the charged particle flux effects on the solid surface. The review paper by A D Korotaev dealt with the amorphization problems of metals and alloys under ion implantation and mixing in metallic films. Great possibilities of mixing for investigation and simulation of amorphization phenomena have been noted-evolution of the pre-amorphization structure and similar features in this structure formation under ion implantation, mixing, and low-temperature diffusion and mechanical agitation were considered, with a critical analysis of current phenomenological and physical amorphization models of metals and alloys. A number of oral papers looked at the phase transitions: A M Panesh et a/, ‘Phase transitions in the presence of point defects in metals irradiated with heavy noble gases’; A E Bekhert et a/, ‘The sequence of phase structure states under ion implantation of carbon, nitrogen and silicon in molybdenum’; and V V Ovchinnikov, ‘Ion-induced phase transitions and atoms rearrangement in metal alloys’. Other papers considered the background for crystalline inclusions and their generation models. For instance, irradiation of metals with noble gas ions may bring about atom/vacancy complexes of a noble gas. As dilation sites, these complexes interact with one another, with the crystalline inclusion initiation, melting and vaporization referred to as phase transitions in the non-perfect gas of the above complexes. In a general case, exposure of metals and alloys to ion beams may result in their anomalous deep structural changes and initiate phase transition occurrence with inward propagation. In the Fe/Ni alloy bombarded with nitrogen ions for example, the transition is observable at a depth to 1 O4 R, (where R, is the mean projected ion range). Non-thermal bcc/fcc phase transitions can also occur under pulsed ion irradiation (1 ms-pulse repetition frequency is 50 Hz) but, unlike the continuous irradiation case, the phase transition occurrence is of a reversible nature, i.e. bcc/fcc to fcc/bcc (N V Gavrilov et a/). The plenary lectures by I I Miroshnichenko, V G Chudinov and E V Kozlov were devoted to radiation and thermal effects illustrated by inorganic oxide systems, atomic generation behaviour of defect accumulations in solids and mechanisms of defective structure formation induced by charged particle beams. 1241