Effects of incidence angles of ions on the mass resolution of an energy compensated 3D atom probe

Abstract We have used a first-order reflectron lens in an optical tomographic atom probe in order to improve the mass resolution. Calculations have been performed to determine the effect of second-order errors in ion energy and incidence angle on the performance of the lens. By applying a correction procedure based on the results of these calculations, we have been able to improve experimental mass resolution by 30%.

Structure of some CoCrFeNi and CoCrFeNiPd multicomponent HEA alloys by diffraction techniques

The structure of CoCrFeyNi (y = 0, 0.8 and 1.2) and CoCrFeNi-Pdx (x = 0.0, 0.5, 0.8, 1.0, 1.2 and 1.5) High Entropy Alloys has been investigated by neutron and standard X-ray as well as by high-energy X-ray diffraction techniques. The alloys were produced by arc melting and afterwards heat treated under several different conditions. It has been concluded that the CoCrFeNi alloy in as-cast condition is, contrary to what is claimed in the literature, not single-phase but consists of at least two different phases, both of fcc type. The difference in lattice constant between the two phases is close to 0.001 Å. Diffraction patterns measured by X-ray and neutron diffraction have shown that the structure of the alloy is not affected by 3 h heat treatment up to 1100 °C. Changing the amount of Fe has no drastic effect on alloy structure. The Pd-containing alloys have also all been found not to be single-phase but to consist of at least four different phases, all being of fcc type. The lattice constants for all phases increase with Pd content. The relative amounts of the different phases depend on Pd concentration. Furthermore, heat treatments of 3 h duration at different temperatures have a significant effect on the alloy phase composition. It is suggested that HEAs should be considered as multicomponent alloys presenting “simple” diffraction patterns, e.g. consisting of one or several lattices of fcc, hcp or bcc type with very close lattice parameters

A STATISTICAL MODEL FOR DERIVING THE MICROSTRUCTURE PARAMETERS OF FINELY DISPERSED SYSTEMS FROM ATOM-PROBE ANALYSES

Un modèle statistique simple pour déterminer les paramètres microstructuraux à partir des données de sonde atomique est décrit. Cette méthode permet de déduire la taille des particules, la fraction volumique et la véritable composition de précipités à partir des profils de concentration expérimentaux.A simple statistical model for determining the microstructural parameters from atom-probe data is described. This method allows to derive the particle size, the volume fraction as well as the actual composition of precipitates from composition profiles obtained experimentally

PRELIMINARY STUDY OF ORDER-DISORDER REACTION IN A Ni3 Fe0.76Al0.24 ALLOY BY MEANS OF ATOM-PROBE TECHNIQUES

L'étude de la mise en ordre dans un alliage Ni3 Fe0.76 Al0.24 a été entreprise à l'aide d'une sonde atomique. L'analyse des plans (001) de surstructure de l'alliage monophasé met en évidence l'alternance de plans mixtes (50 % Ni, 50 % Fe, Al) avec des plans purs de Ni. Une rupture de séquence dans l'empilement de ces plans a été observée et reliée à l'existence d'une paroi d'antiphase entre domaines ordonnés. La composition des phases existant à plus hautes températures a pu être déterminée en dépit de la faible différence de composition entre précipités et matrice et de la faible taille des particules.Atom study of ordering in a Ni3 Fe0.76 Al0.24 has been undertaken. Analyses of the (001) superstructure planes of the one phase alloy exhibit the alternation of mixed planes (50 % Ni, 50 % Al, Fe) with pure planes (100 % Ni). A rupture of this stacking sequence was observed and has been correlated to the occurence of an antiphase boundary between ordered domains. Composition of phases existing at higher temperatures has been determined in spite of the weak difference between matrix and precipitate composition and the small particle size

Contribution of 3D atom probe to the understanding of plane-by-plane AP analyses data: application to the study of ordering in Cu3Au

International audienc

Contribution of 3D atom probe to the understanding of plane-by-plane AP analyses data: application to the study of ordering in Cu3Au

International audienc

ATOM-PROBE INVESTIGATION OF THE EARLY STAGES OF DECOMPOSITION IN A NICKEL-BASE SUPERALLOY

A conventional time of flight atom-probe has been used for the investigation of the early stages of precipitation of γ' phase in a nickel base superalloy. The microstructure parameters, as derived from concentration profiles, have been studied as a function of the aging time at 650°C. For aging times smaller than a few hours, the precipitate composition varies in a large extent while the particle size remains nearly constant. In contrast, in the coarsening stage γ' precipitates reach their equilibrium composition after the first 25 hours

Phase composition and chemical order in the single crystal nickel base superalloy MC2

International audienceThe time evolution of phase composition at 1050°C in a new single crystal nickel base superalloy (MC2) recently developed, is studied by means of atom-probe techniques. The results indicate that the composition of both γ and γ′ phases evolves drastically during ageing. The composition of the μ phase was estimated for 100 h at 1050°C. Atom-probe data demonstrate that μ is a Ta, W, Mo enriched-phase. No impoverishment effect of the γ solid solution related to the μ phase precipitation was detected. The spatial distribution of μ-forming elements in the γ phase was investigated in order to find out whether clustering occurs. Ordering phenomena related to chromium were observed in γ. The long range order in the γ′ phase was also studied. The microanalysis of the material on a (001) superstructure plane allowed the preferential sites of various species to be determined. \textcopyright 1993

ATOM PROBE STUDY OF TITANIUM BASE ALLOYS : PRELIMINARY RESULTS

Deux alliages à base titane, Ti46 Al54 et Ti88,8 Cu2,3 Al8,9, ont été étudiés à la sonde atomique. Un précipité de la phase Ti2 Al a été analysé dans l'alliage binaire. La microanalyse de l'alliage Ti Cu Al a révélé la présence de zones enrichies en Cuivre. L'étude a également mis en évidence une pénétration d'Hydrogène dans les échantillons probablement due à la technique de préparation. Les résultats obtenus démontrent la faisabilité d'études d'alliages à base titane à la sonde atomique.Two different titanium base alloys, Ti46 Al54 and Ti88.8 Cu2.3, Al8.9, have been studied by atom probe microanalysis. A precipitate of Ti2 Al was analysed in the binary alloys. Micro-analysis of Ti Cu Al alloy revealed the presence of Copper enriched zones. The study has also exhibited a penetration of Hydrogen in the samples, probably due to preparation technique. The results demonstrate the feasibility of studies on titanium base alloys by mean of atom probe

ATOM-PROBE INVESTIGATION OF THE EARLY STAGES OF DECOMPOSITION IN A NICKEL-BASE SUPERALLOY

A conventional time of flight atom-probe has been used for the investigation of the early stages of precipitation of γ' phase in a nickel base superalloy. The microstructure parameters, as derived from concentration profiles, have been studied as a function of the aging time at 650°C. For aging times smaller than a few hours, the precipitate composition varies in a large extent while the particle size remains nearly constant. In contrast, in the coarsening stage γ' precipitates reach their equilibrium composition after the first 25 hours