Papers by Keyword: Auger Electron Spectroscopy (AES)

Abstract: Nitrogen implanted titanium alloys with enhanced wear resistance have been synthesized under the conditions of energy and N++N2 +ion dose in the range of 30keV to 120keV and 3×1017ions/cm2 to 1×1018ions/cm2, respectively. Auger electron spectroscopy and X-ray diffraction show that supersaturated titanium solid solution with the gradient nitrogen concentration and titanium nitride compounds are formed in the surface modified regions of the materials. Enhanced wear resistance of the nitrogen implanted titanium alloy at energy of 120keV and ion dose of 1×1018ions/cm2 has been showed and explained on the basis of observed microstructure including the formation of micropits on the wear track in the present study.

Abstract: Specific studies were carried out on the characteristic component from interior surfaces (IS) of cavities in metallic fire debris by Auger electron spectroscopy (AES), especially in order to distinguishing the primary and secondary electrical short circuit (ESC) arc beads. From the results of AES, we can see that the components from interior surfaces of cavities in the primary and secondary ESC are different, which help in probing the cause of the fire.

Abstract: Ordered reconstruction phases on the 4H-SiC(1102) surface have been investigated using low-energy electron diffraction (LEED), Auger electron spectroscopy (AES) and scanning tunneling microscopy (STM). After initial hydrogen etching, the samples were prepared by Si deposition and annealing in ultra-high vacuum (UHV). Two distinct reconstruction phases develop upon annealing, first with a (2×1), and at higher temperatures with a c(2×2) LEED pattern. After further annealing the fractional order LEED spots vanish and a (1x1) pattern develops. For the (2×1) phase, STM micrographs show that adatom chains develop on large flat terraces, which in view of AES consist of additional Si. These highly linear and equidistant chains represent a self-assembled well-ordered pattern of nanowires developing due to the intrinsic structure of the 4H-SiC(1102) surface. For the c(2×2) phase AES indicates a surface composition close to the bulk stoichiometry. For the (1×1) phase a further Si depletion is observed.

Abstract: The mechanism of the degradation process of nickel based superalloy CM247LC under creep loading was analyzed by considering the microscopic chemical composition of the material such as phase boundary of γ and γ’ phases. In this study, a Directionally Solidified (DS) nickel-based superalloys CM247LC was used as test specimens. The creep test was performed at 900oC under an uni-axial stress of 216 MPa. Each specimen was creep ruptured and interrupted at different hours and then analyzed. The change of chemical composition around the interface analyzed precisely by used Auger Electron Spectroscopy (AES). It was found that the local enrichment or lack of cobalt and chromium was found at the interface. This tendency was not found in the stress free area. Since chromium is the well-known element that dominates the degradation of this material, such an enrichment or lack of cobalt and chromium may play an important role for forming a crack propagation path near the interface. This local segregation should be analyzed further to make clear degradation mechanism of this material.

Abstract: Structural properties of Ni/Ti films deposited on 4H-SiC and annealed at temperatures from 800 to 1040°C have been studied. Films with three different metal deposition sequences were investigated by X-ray diffraction and Auger electron spectroscopy: (A) Ti(100 nm)/Ni(50 nm); (B) Ti(4 nm)/Ni(50 nm)/Ti(100 nm); and (C) Ti(4 nm)/Ni(150 nm). A distinct spatial separation of nickel silicide and titanium carbide layers was observed in all samples. It was discovered that the distribution of the products of the solid state chemical reaction in samples (A) and (B) was independent on the deposition sequence of Ti and Ni layers. The titanium carbide layer located on the interface and covered by the clearly separated nickel silicide layer was detected in both samples after heat treatments.

Abstract: We have used depth-resolved cathodoluminescence and Auger electron spectroscopies, DRCLS and AES, respectively, to probe the electronic structure and the composition of Ti/Al ohmic contacts to p-type SiC on a nanometer scale. A continuous Ti-Si-C compound layer was observed using the Auger depth profile. No interfacial Al segregation was found. The secondary electron threshold technique showed a continuous decrease in work function from the p-type SiC to the Ti-Si-C compound layer. Our results support an ohmic contact mechanism by an intermediate semiconductor layer which reduces the otherwise large interfacial Schottky barrier height. DRCLS revealed a ~2.78 eV sub-band gap transition enhanced by interfacial reaction in the near-interface SiC, suggesting the formation of additional C or Si vacancies.

Abstract: The present work is part of a broader investigation of the effects of additives in zinc phosphate (ZPO) coating solutions that are designed for specific applications to Al and its alloys. ZPO conversion coatings improve the corrosion resistance of the Al substrate and increase the adhesion of paint. Coatings formed on 2024-T3 aluminum alloy, after dipping in ZPO coating baths containing Mn2+, have been studied by X-ray photoelectron spectroscopy (XPS), SEM, and scanning Auger microscopy (SAM). Variations are observed in coating morphology and composition as the amount of Mn2+ in the coating solution increases through the 0 to 2500 ppm range. Adhesion tests give information on the relative strength of the coating-substrate interaction at different microstructural areas.

Abstract: Theoretical base for non-destructive diffusion parameters determination technique in solids taking into account the dopant flux from the sample surface is presented. Diffusion of the nitrogen implanted in the tungsten single crystals was determined in temperature range 700–820°C. Surface concentration of nitrogen was obtained by Auger electron spectroscopy. Initial distribution of the nitrogen in subsurface region was measured by secondary-ion mass-spectroscopy. Two dopant atom fluxes found in subsurface region of the ion-implanted material are supposed to connect with the radiation damages and with the bulk diffusion mechanism.

Abstract: The effects of cold working and heat treatment on caustic stress corrosion cracking (SCC) of mill annealed (MA) alloy 800M in boiling solution of 50%NaOH+0.3%SiO2+0.3%Na2S2O3 were investigated by means of microstructure examination, tensile test, X-ray stress analysis, SCC testing of C-rings, Auger electron spectroscopy (AES), scanning electron microscopy (SEM) and metallography. The microstructure of alloy 800M under tested conditions was austenite. With a strain of 25% by cold working, the grains of alloy 800M became longer, yield strength (YS) and ultimate tensile strength (UTS) increased, elongation (δ ) decreased, residual stress and the susceptibility to SCC increased. With increasing temperature of heat treatment of alloy 800M with cold working, the grains became bigger , residual stress, YS and UTS decreased and δ increased, the susceptibility to SCC of alloy 800M decreased. In boiling caustic solution, SCC cracks on the surfaces of C-ring specimens polarized potentiostatically at –20mV/SCE initiated from pitting and propagated along grain boundaries. AES analysis indicated that the surface films on MA alloy 800M were enriched in nickel and depleted in iron and chromium.