[en] Falex wear tests on mild (SAE 3135) steel samples treated by either nitrogen implantation (2.5x10¹⁷ N₂⁺ cm^-2 at 180 keV) or low temperature (about 315⁰C) oxidation are reported. The results show that both treatments lead to about an order-of-magnitude reduction in the long-term wear rate of the steel. In addition to the wear rate measurements, the wear member asymmetry behavior, scanning electron microscopy studies, Auger spectra and sputter profiles all indicate that the wear modes induced by both treatments are the same and are oxidative wear. These results confirm the previously proposed initiator-sustainer wear model in which implanted nitrogen simply acts as an initiator of favorable oxidative wear but is not directly involved in maintaining the sustained wear resistance. Possible mechanisms for both the initiation process and the sustained wear process are reviewed and discussed. (orig.)

[en] Polycrystalline type 316 stainless steel has been fatigued in air and in vacuum at 600⁰C at two constant plastic strain amplitudes. Although in air the curve of cyclic stress versus number of cycles is prematurely interrupted by failure, in vacuum it is sufficiently extended to allow secondary cyclic hardening to occur. Transmission electron microscopy observations show dislocation configurations (during the fatigue life) which are similar for both strain amplitudes. During the saturation plateau, several configurations coexist: regular walls, a labyrinth structure and persistent slip bands (PSBs) with a ladder structure. At failure (in vacuum) a cellular structure widely prevails while a labyrinth structure and PSBs with a ladder structure no longer exist. (orig./IHOE)

[en] Analysis using γ-ray emission by charged-particle activation is employed to determine the amounts of carbon and oxygen at the surfaces of Jordanian steel. The irradiation source was provided by the 4.75 MeV Van de Graaff accelerator at the University of Jordan. This method is very selective and gives a high detection limit for light elements at metal surfaces. (orig.)

[en] During ion implantation the phase stability and implanted ion composition are strongly affected by the radiation damage inherent in the process. A study was made of the role of radiation damage processes in the implantation of silicon into nickel at temperatures from 25 to 650⁰C. Radiation-induced segregation occurred, resulting in a greatly enriched silicon content on substrate surfaces. The crystalline nickel silicide phases, Ni₅Si₂, Ni₂Si and NiSi₂, were observed over a wide temperature range, including T<200⁰C. The Ni₃Si phase, however, was destabilized by radiation damage and formed only at T>500⁰C. At T>250⁰C and fluences near or exceeding 1x10¹⁸ Si⁺ cm^-2, the implanted layer recrystallized. Penetration of implanted silicon several thousand angstroems beyond the ballistic range of the implanted ions was also observed at these fluences for T>350⁰C. A microcrystalline phase formed in this fluence range at T<200⁰C. (orig.)

[en] Polycrystalline or single-crystal aluminium sheets with a purity of 99.99% were implanted with nitrogen ions (N₂⁺) at energies of 50, 100 and 150 keV at room temperature and fluences ranging from 1x10¹⁶ to 1x10¹⁸ ions cm^-2 (2x10¹⁶-2x10¹⁸ nitrogen atoms cm^-2). The surface structure, chemical composition and chemical bond of the implanted aluminium surface layer were investigated by Auger electron spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, transmission electron diffraction, transmission electron microscopy and IR spectroscopy. Furthermore, the microhardness of the nitrogen-implanted aluminium surface was evaluated by measuring the penetration depth with an applied load. From the characterization of the nitrogen-implanted aluminium layer, high fluence ion implantation into aluminium can result in the formation of polycrystalline or single-crystal aluminium nitride (AlN) layers at room temperature without any thermal annealing. It was found that nitrogen implantation into aluminium was effective in enhancing the hardness of the aluminium surface, which is attributed to the formation of the crystalline AlN produced by nitrogen implantation. (orig.)

[en] The physical state of neon implanted into different metals has been studied by means of soft X-ray emission spectroscopy. Metal samples (beryllium, aluminium, titanium, chromium, iron, copper, zinc, molybdenum, silver, tungsten, gold, lead and bismuth) are implanted with 50 keV neon ions (²⁰Ne⁺) and subsequently irradiated with 4 keV electrons to excite the neon X-ray fluorescence which is analysed with a flat-crystal spectrometer. A considerable broadening of the atomic K X-ray line is observed for all samples, showing the existence of a band structure. The observed 2p band with W ranges between 1.95 and 4.07 eV depending on the host metal (compared with 1.3 eV for solid neon at atmospheric pressure). X-ray fluorescence analysis yields two observations (the total width W and the spectrum shape) which should be related to the following macroscopic parameters: The average metal shear modulus μ and the internal pressure. A plot of W vs. shear modulus shows a relation which can be approximated by the following straight line (where W is in electronvolts and μ in gigapascals): W = 0.017μ + 1.3. Using the relationship between the shear modulus and the pressure, it is thus possible to relate W to the pressure. (orig.)

[en] Nitrogen implantation into steels is certainly the most well-known case of the improvement obtained in wear resistance using implantation. To a large extent, tribological results depend on the steel composition but also on the implantation conditions (fluence, temperature and vacuum quality). Both aspects will be discussed. In the evolution of the implanted layer, the combined influence of the newly created phases, the residual stresses and the nitride grain size must be of primary importance even if they are not always fully controlled. These are studied as a result of the thorough characterization of the implanted region which has been performed by numerous researchers and will be reviewed here. The study consists first in plotting the distribution of the implanted element with a good depth resolution (Auger electron spectroscopy, secondary ion mass spectrometry and nuclear reaction analysis), secondly in measuring the grain sizes (transmission electron microscopy) and thirdly in identifying the compounds formed during implantation (conversion electron Moessbauer spectroscopy, grazing-angle X-ray diffraction, electron spectroscopy for chemical analysis, transmission electron microscopy etc.). With respect to the characterization of the implanted region, recent results will be reported and in particular those concerning the preferential orientation of the nitride and carbonitride phases under irradiation. (orig.)

[en] A facility for wear tests under simulated production conditions was installed. These tests permit variations in essential parameters of the forming processes 'backward can extrusion' and 'upsetting between flat parallel dies', which were investigated in this work. For measuring sufficient wear, 10 000 to 20 000 workpieces had to be pressed. To reduce the time, in some cases a short-time testing procedure based on a radionuclide technique was used. In this, thin surface layer of the tool was activated by deuteron irradiation. During the wear process the activity of the tool decreased because of loss of material. This enabled the determination of wear after only 2000-3000 manufactured workpieces. By applying nitrogen-ion-implanted tools, wear decreased down to the level of conventionally nitrided tools. The great advantage of the former process is the low temperature of treatment; so the roughness and structure of the material are not affected and tools can be machined to their final dimensions before ion implantation. The results of nitrogen implantation are compared with those of nitrogen plus silver ion implantation and nitrogen plus tin ion implantation. A comparison of the two forming processes, different tool materials and various surface treatments should contribute to economic application of optimized wear-resistant tools in bulk metal forming processes. (orig.)

[en] Ion implantation makes possible unique metal surface characteristics that have found widespread applications. The still developing implanter technology offers a variety of systems suited to different purposes. The types of ion source are described in terms of attributes which influence the choice of a source for a particular application. Extractors are discussed to a lesser extent, and other system parts are mentioned briefly. Although present semiconductor ion implanters deliver 10-20 mA, the technology can be extended easily to over 100 mA, especially when mass analysis is not required. For large-area applications, the ion source can be one of several designs based on magnetic cusp confinement of a plasma containing the ion of interest. (orig.)

[en] Nickel substrates were implanted with 180 keV aluminum ions (Al⁺) to fluences near 10¹⁸ ions cm^-2. The resulting aluminum concentration profiles and microstructures were examined after implantation and following annealing at temperatures below 800⁰C. The phases detected after annealing were consistent with both the Ni-Al equilibrium phase diagram and the aluminum concentrations in the implanted layers. The concentration profiles changed only slightly during annealing below 650⁰C for fluences less than 1.4x10¹⁸ Al⁺ cm^-2. At fluences above this, however, the aluminum concentration profiles after annealing at 650⁰C extended to depths approaching 8000 A, at least 4000 A deeper than the as-implanted profiles. The aluminum concentration near the surface decreased during annealing, consistent with conservation of total aluminum content and extension of the profiles. The kinetics of the decrease in near-surface aluminum content were followed in situ by measuring the IR emissivities of the specimens, which correlated with their near-surface aluminum concentrations. The aluminum concentrations were constant with annealing time for specimens implanted to less than 1.4x10¹⁸ Al⁺ cm^-2. For higher fluences the emissivities and aluminum contents changed by a factor of 3 over annealing time periods that increased with decreasing temperatures. The diffusion coefficients derived from the aluminum concentration dependence on time ranged from 1.1x10^-13 to 21x10^-13 cm² s^-1 for specified annealing temperatures between 500 and 800⁰C. The activation energy for this diffusion, 62 kJ mol^-1, is close to that ascribed to grain boundary diffusion in Ni₃Al, 50 kJ mol^-1. The nickel behind the implanted layers recrystallized during annealing, providing the necessary grain boundary diffusion paths. (orig.)