Papers by Miklos Menyhard
Tungsten Carbide Nanolayer Formation by Ion Beam Mixing with Argon and Xenon Ions for Applications as Protective Coatings
ACS Applied Nano Materials
Acta Physica Hungarica, 1985
Surface and Coatings Technology, 2019
HIGHLIGHTS A novel method was demonstrated for the production of SiC micro and nanopatterns P... more HIGHLIGHTS A novel method was demonstrated for the production of SiC micro and nanopatterns Patterning and SiC compound formation happened in one step at room temperature The SiC formation was proved by AES depth profiling Two different patterns were presented The method can be considered as a possibility to fabricate SERS substrates
Quasi-static intergranular cracking in a Cu/1bSn alloy; an analog of stress relief cracking of steels
Scripta Metallurgica et Materialia, 1992
This paper is related to the general problem of time-dependent intergranular fracture which appea... more This paper is related to the general problem of time-dependent intergranular fracture which appears to result from a loss of cohesion along grain boundaries, induced by the concentration of an embrittling element in the boundaries as a result of the application of a stress. The prototypical example of this phenomenon is the brittle mode of stress-relief cracking (SRC) in steels,
Scripta Metallurgica et Materialia, 1991
In~rmd~ ion Many interesting and sometimes harmful processes like temper embrittlement, stress co... more In~rmd~ ion Many interesting and sometimes harmful processes like temper embrittlement, stress corrosion cracking, grain boundary diffusion, etc., are governed or at least strongly influenced by grain boundary segregation (GBS): thus, its study is of great technical importance. Auger fractography has been the most important method for the experimental approach of studying GBS. By using this method, one produces a brittle specimen. This specimen is to be fractured in situ in the Auger Electron Spectroscope (AES). The fracture surface, supposed to be the grain boundary (GB), is analyzed by means of AES. It is generally supposed that the bonds on the two sides of the grain boundary plane are broken statistically equally, resulting, on a macroscopic scale, in an even distribution of the segregated atoms on both newly created surfaces. Thus, the coverage measured on one of the fracture surfaces is to be multiplied by two to get the GB coverage. It has been known for a long time that the coverage of the segregated atoms on the fracture surface might show strong variability [1-5]. The number of these findings increases with the number of Auger Microprobes available with high spatial resolution. The essential question in this situation is whether or not the variability observed on the fracture surface reflects the variability of the segregated element on the corresponding GB-s? It was shown that single crystal effects (practically all measurements, using Auger Microprobes, are done on a given facet, that is on a single crystal) can result in a variability of the measured Auger signal even in the case of homogeneous coverage [6-7]. There are rough estimates on the size of this "artifact" [3,8]. An additional source of the variability is the uneven distribution of the segregated atoms during the fracture process. This obviously results in a real physical variability which, on the other hand, does not reflect the original variability of the coverages of the segregated elements on the GB-s. The possibility of the uneven distribution of the segregated atoms during the fracture process was considered a long time ago [9], which is not surprising from a theoretical point of view. In fact the atomistic modelling of the GB has proved that the GB is a well organized region, having a well defined structure. The different GB structures show different capabilities to accept segregating atoms, resulting in various coverages and atomic arrangements on various GB-s. The positions of the segregated atoms are not necessarily symmetrical with respect to the two grains: thus, there is no good reason to suppose that the fracture always distributes the segregated atoms evenly between the fracture surfaces. Only a few works are known, where both sides of the fracture were measured. Suzuki et al. [9] measured the level of segregation on one side of the fracture of a Fe-P alloy, and after it, the structure of the studied facets
Grain boundary segregation and transformations in Bi-doped polycrystalline copper
Acta Metallurgica, 1989
... BOUNDARY SEGREGATION AND TRANSFORMATIONS IN Bi-DOPED POLYCRYSTALLINE COPPER M. MENYHARD,f B. ... more ... BOUNDARY SEGREGATION AND TRANSFORMATIONS IN Bi-DOPED POLYCRYSTALLINE COPPER M. MENYHARD,f B. BLUM and CJ McMAHON Jr Department ... and is analogous to the phase transition from segregated carbon to monolayer-graphite observed by Shelton al ...
On the effect of molybdenum in the embrittlement of phosphorus-doped iron
Acta Metallurgica, 1989
ABSTRACT In an effort to clarify the effects of molybdenum, which greatly retards the kinetics of... more ABSTRACT In an effort to clarify the effects of molybdenum, which greatly retards the kinetics of temper embrittlement of alloy steels, the incidence of intergranular fracture and the segregation of phosphorus and other elements to grain boundaries were studied in a series of Fe-Mo-P alloys by means of fracture experiments in a high-resolution scanning Auger microprobe. Decarburization was necessary to produce intergranular fracture in these alloys, which originally contained residual carbon. This element was the principal determinant of the tendency for intergranular fracture. There was no evidence of scavenging or retardation of diffusion of phosphorus by molybdenum. The results were analyzed to determine the existence and importance of synergistic cosegregation of molybdenum and phosphorus. The evidence based on the mean values of the grain boundary concentrations was ambiguous and inconclusive. However, consistent support for the coseregation model could be produced by use of a spectrum of segregation energies, based on the broad spectrum of grain boundary concentrations observed experimentally and presumed to result from the spectrum of grain boundary structures. It is proposed that this kind of analysis is physically more realistic than one which employs mean values. Using this model the attractive interaction between molybdenum and phosphorus in iron was deduced to be weaker than heretofore believed; this finding is consistent, however, with other recent work. The interaction is too weak to influence the segregation of the phosphorus, but it should promote the segregation of molybdenum, absent the effects of other elements like sulphur and carbon. The interaction between molybdenum and carbon appears to be the dominant factor which influences grain boundary cohesion in these alloys.RésuméPour tenter de clarifier les effets du molybdène, qui retarde de façon importante de cinétique d'adoucissement par revenu des aciers alliés, nous avons étudié dans différents alliages Fe-Mo-P l'incidence de la rupture intergranulaire, ainsi que la ségrégation du phosphore et d'autres éléments dans les joints de grains, en réalisant des expériences de rupture dans une microsonde Auger à balayage et à haute résolution. Il a été nécessaire de décarburer ces alliages, qui du départ contiennent du carbone résiduel, pour y observer une rupture intergranulaire. Cet élément est le déterminant principal de la tendance à la rupture intergranulaire. Il ne semble pas y avoir de preuve de perte ou de retard de diffusion du phosphore par le molybdène. Les résultats sont analysés pour déterminer l'existence et l'importance de la coségrégation synergétique du molybdène et du phosphore. Les valeurs moyennes des concentrations intergranulaires ne fournissent qu'une preuve ambiguë ne permettant pas de conclure. Néanmoins, l'utilisation d'un spectre d'énergies de ségrégation—basé sur le spectre large des concentrations intergranulaires observé expérimentalement et supposé dériver du spectre des structures intergranulaires—pourrait fournir un support logique au modèle de coségrégation. Cette sorte d'analyse nous paraît physiquement plus réaliste que celle qui utilise les valeurs moyennes. A partir de ce modèle, nous déduisons que l'interaction attractive entre le molybdène et la phosphore dans le fer est plus faible que ce que l'on croyait jusqu'à présent; cette constatation est en accord, cependant, avec un autre travail récent. L'interaction est trop faible pour influencer la ségrégation du phosphore, mais elle devrait favoriser la ségrégation du molybdène en l'absence des effets d'autres éléments tels que le soufre et le carobne. L'interaction entre la molybdène et corbone semble être le facteur prédominant qui influence la cohésion intergranulaire dans ces alliages.ZusammenfassungAn einer Reihe von Fe-Mo-P-Legierungen wurde das Auftreten des intergranularen Bruchs und die Segregation von Phosphor und anderen Elementen an Korngrenzen untersucht. Hiermit sollte der Einfluß des Molybdäns aufgeklärt werden, welches die Geschwindigkeit der Temperversprödung von legierten Stählen stark verlangsamt. Hierzu wurden Bruchexperimente in einer hochauflösenden Auger-Mikrosonde durchgeführt. Für den intergranularen Bruch dieser Legierungen die ursprünglich Restkohlenstoff enthielten, war Entkohlung notwendig; dieses Element war auch ausschlaggebend für die Neigung zum intergranularen Bruch. Hinweise auf einen Reiningungseffekt oder auf verzögerte Diffusion von Phosphor und Molybdän fanden sich nicht. Die Ergebnisse wurden analysiert, um Aussagen über über das Vorhandensein und die Wichtigkeit der synergistischen Kosegregation zu erhalten. Ergebnisse, die auf einer Auswertung mit mittleren Konzentrationen an den Korngrenzen beruhen, waren mehrdeutig und ließen keinen klaren Schluß zu. Allerdings konnte mit einem Spektrum von Segregationsenergien das Modell der Kosegregation…
Determination of effective electron inelastic mean free paths in SiO2 and Si3N4 using a Si reference
Surface Science, 2003
Elastic peak electron spectroscopy (EPES) provides inelastic mean free path (IMFP) values in the ... more Elastic peak electron spectroscopy (EPES) provides inelastic mean free path (IMFP) values in the near-surface region. Such values, which will be called effective IMFPs, might be different from these derived from bulk parameters. In this work we derive effective IMFP values from EPES measurements in the range of 300–2000 eV for SiO2 and Si3N4 using a Si reference. Corrections for
Surface and Interface Analysis, 2010
Electron spectra are generally presented in arbitrary units. The experimental elastic peak intens... more Electron spectra are generally presented in arbitrary units. The experimental elastic peak intensity Iespec(E) is determined by the elastic backscattering probability Ie(E) of electrons backscattered elastically within the solid angle of the spectrometer. The experimental elastic peak Iespec(E) is converted to Ie(E) backscattering probability using our new procedure based on the Goto ie(E) elastic backscattering current database. The elastic backscattering probability Ic(E) was calculated applying the EPESWIN software of Jablonski. Ie(E) < Ic(E) due to the surface losses of electrons, characterized by the surface excitation parameter Pse (SEP). Pse(E) was determined experimentally using the Goto database and the relationship of Tanuma. Our new procedure is applied to angular‐resolved (AREPES) spectra of Jablonski and Zemek presented in arbitrary units. In their AREPES experiments, the experimental elastic peak intensity Iespec = Ie(E, αd, ΔΩ) was measured at αd angle of detection...
Scripta Metallurgica, 1983
In-depth distribution of ion beam damage in SiC
Vacuum, 2012
In this paper we report on the ion beam bombardment-induced alteration of SiC measured at differe... more In this paper we report on the ion beam bombardment-induced alteration of SiC measured at different ion energies (300–1700 eV) and at wide range of incident angle (43°–87°). Surface roughening was reduced by sample rotation during sputtering. The change of the concentration was characterized by Auger electron spectroscopy. Both low and high energy Auger peaks of Si were detected, which allowed us to estimate the depth distribution of the components. The observed alteration of Auger peak heights will be explained by simple model of the changed in-depth distribution. The model gives an estimate for the composition of top layer (the real surface) of SiC in different sputtering conditions, as well as the in-depth distribution of Si and C.
Vacuum, 1983
In order to understand the parameters affecting the properties of NiCr resistors prepared by vari... more In order to understand the parameters affecting the properties of NiCr resistors prepared by various methods, the annealing properties of NiCr thin films were studied. TEM and electron diffraction were used to determine the structure of the films deposited onto SiOx coated microgrids, while electrical measurements and AES indepth profiling were carried out on the samples deposited under identical conditions onto silica substrates. The effect of a SiOx protective coating on the structural changes was investigated during high temperature annealing in vacuum. In the NiCr samples annealed without a protective layer the selective oxidation of chromium led to a rather metallic type of conduction, while in the protected samples the stabilization of the conduction was observed after the same annealing. By hindering oxidation and surface diffusion processes the protective layer resulted in the development of a more stable structure in the NiCr films.
Surface Science, 2003
Ion sputtering induced surface composition changes by applying various ions (He þ , Ne þ , Ar þ ,... more Ion sputtering induced surface composition changes by applying various ions (He þ , Ne þ , Ar þ , Xe þ) in the energy range of 0.2-1.5 keV, was measured by AES on the polar faces of 6H-SiC{0 0 0 1}. Carbon enrichment was observed on both faces, and it was different if Ne þ , Ar þ , Xe þ ion sputtering was applied with ion energy lower than 0.4-0.8 keV (depending on projectile); no different enrichment was found for He þ ion bombardment at any energy (in this range). Thus C/Si ratio measured by AES after low energy ion (e.g. Xe þ) bombardment can be used to identify polarity of the surface.
Surface Science, 2010
A multilayer sample (C (23.3 nm)/Ta (26.5 nm)/C (22.7 nm)/Si substrate) was submitted to AES dept... more A multilayer sample (C (23.3 nm)/Ta (26.5 nm)/C (22.7 nm)/Si substrate) was submitted to AES depth profiling by Ar + ions of energy 1 keV and angles of incidence of 72°, 78°, and 82°. The shapes of the asmeasured depth profiles were strongly different emphasizing that the ion-bombardment conditions strongly affects the shapes of measured depth profiles. We simulated the depth profile measured at an angle of incidence of 72°by calculating the backscattering factor, applying attenuation lengths available in the literature, and simulating the ion-bombardment-induced specimen alteration with a TRIDYN simulation and a trial and error method. The good agreement between the calculated and measured depth profiles justified the method applied.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1994
AES depth profiling was carried out on a Ge-Si multilayer structure using rotated specimen and gr... more AES depth profiling was carried out on a Ge-Si multilayer structure using rotated specimen and grazing incidence angle. Under these sputtering conditions the depth resolution is determined mainly by atomic mixing. The dependence of the experimentally measured atomic mixing on incidence angle and energy was compared with the simulation results obtained from TRIM code. It was found that the trends of the dependencies were the same, but the TRIM predicted weaker atomic mixing than that of the experimental one. Thus we concluded that consideration of the thermal processes is also important in the description of the atomic mixing in the Ge-Si system.
Metallurgical Transactions A, 1983
Study of ion mixing during Auger depth profiling of Ge–Si multilayer system. II. Low ion energy (0.2–2 keV) range
Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 1995
Auger electron spectroscopy depth profiling was carried out on amorphous Ge–Si multilayer structu... more Auger electron spectroscopy depth profiling was carried out on amorphous Ge–Si multilayer structures of 2 and 3 nm layer thicknesses using a dedicated Auger depth profiling instrument that rotates the specimen during sputtering and applies a grazing angle of incidence. Ion energy was in the range of 0.2–2 keV. The depth profiles of these multilayer systems are oscillating functions. The authors show that the amplitude of the oscillation versus the square root of the ion energy curve is linear in the energy range used. The depth profile cannot be described either by Gaussian broadening or the Liau model. Simulations using the dynamic transport of ions in matter code reproduce the slopes of the amplitude of oscillation versus the square root of ion energy curves, but the simulated and measured intercepts are different. The ratios of the measured and simulated intercepts are constant and do not depend on the layer thickness. This is used to give a recipe for a ‘‘normalization’’ of the ...
Applied Surface Science, 2001
An investigation has been made of the thin-®lm structure and interface morphology of giant magnet... more An investigation has been made of the thin-®lm structure and interface morphology of giant magnetoresistance (GMR) spin valves of the cobalt/copper/cobalt (Co/Cu/Co) type that were grown on polycrystalline NiO substrates at three different temperatures (150, 300 and 450 K). Sputter-depth-pro®le analyses indicate that the quality of the layering in the Co/Cu/Co structure was only slightly better for the 150 K sample than for the 300 K sample. For the 450 K sample, however, the Co/Cu/ Co structure showed extensive disruption. The similarity in the depth-pro®les for the 150 and 300 K samples indicates the sensitivity of the GMR to subtle structural differences.
Applied Surface Science, 2005
The steady state surfaces of ion bombarded 3C-, 4H-and 6H-SiC samples were studied by means of re... more The steady state surfaces of ion bombarded 3C-, 4H-and 6H-SiC samples were studied by means of reflected electron energy loss spectroscopy (REELS). The REELS exhibit a well-defined loss peak in the region of about 20 eV. The position of the maximum of the loss peak depends on the bombarding ion energy (decreasing with increasing ion energy), and on the primary electron beam energy (increasing with increasing primary energy). This behavior can be explained if we suppose that the plasmon energy in the altered layer (produced by ion bombardment) is different from that of the unaltered bulk. In this case the measured loss peak is the sum of two overlapping plasmon peaks. With modeling the system as a homogeneous altered layer and a homogeneous unaltered substrate the plasmon energy in the altered layer was derived to be 19.8 eV. The large change of the plasmon energy with respect to the bulk value of 23 eV is explained by a thin low density overlayer on the surface of the sample produced by the ion bombardment.
Acta Metallurgica et Materialia, 1991
Abstraet-A high-resolution scanning Auger microprobe analysis was carried out on matching fractur... more Abstraet-A high-resolution scanning Auger microprobe analysis was carried out on matching fracture surfaces of symmetrical E = 5 (013) bicrystals of Fe-3 wt%Si doped with 270ppm phosphorus which were grown from seeds by floating-zone melting. The phosphorus distribution on some regions of a fracture surface was found to alternate between high and low concentrations; these alternations were often associated with deformation bands, such as mechanical twins. The reverse pattern was found on the matching region on the opposite fracture surface. This confirms a hypothesis made earlier that the inhomogeneous phosphorus concentrations found on fracture surfaces are the result of off-center crack propagation through a laterally extended phosphorus distribution along the grain boundary and the switching of the crack path from one side to the other upon an encounter with a grain-boundary step caused by a deformation band. In the regions of unequal division of the P-enriched region by the fracture, a 2: 1 ratio of phosphorus concentrations was found. The total width of the region was deduced to be about five atomic planes from observations of sputtering rates and an analysis based on simple logic.
Uploads
Papers by Miklos Menyhard