Papers by Keyword: Electron Probe Microanalysis

Abstract: Interdiffusion in Ni-base superalloy CMSX-4 and alloys related to CMSX-4 was investigated at the temperature 1288 °C, which is 8 °C above the γ’-solvus temperature of this superalloy, 1280 °C. This temperature is of a special interest because it is a temperature of hot isostatic pressing applied to CMSX-4 and modeling of this process needs verified diffusion data for this specific temperature. Various diffusion couples were assembled from the investigated alloys, annealed at 1288 °C and studied by electron probe microanalysis. So far as the annealing temperature was higher than the γ’-solvus temperature of CMSX-4 and other investigated alloys have no strengthening γ’-phase, interdiffusion occurred in the fcc solid solutions of nickel. It was found that in the case when the γ’-forming and γ-stabilizing elements diffuse in the same direction (towards nickel) the diffusion rate accelerates, but when they diffuse in the opposite directions (counter diffusion) it slows down. Such an interdiffusion behavior is in agreement with the results predicted with diffusion simulation software Dictra.

Abstract: The article reviews the results of experimental studies of microstructure and redistribution of alloying elements in heat-resistant alloy HN45VMTYUBR during laser beam welding (alloy produced according to GOST 5632-14). Impression of laser emission on redistribution of alloying elements throughout the depth of a welding seam is demonstrated. Analysis covers the microstructure of several welding and heat-affected zones and redistribution of the alloying elements in these zones. Increase in tungsten content in weld root is detected. Redistribution of alloying elements in welding zones is proven to impact strength characteristics of the seam.

Abstract: Development of rare earth doped silica fibre fabrication using MCVD furnace chelate vapor phase delivery is presented. In this study, erbium and aluminium is used as the dopant with precursor erbium (III) tris (2,2,6,6-tetramethyl-3,5-heptanedionate) and aluminium chloride respectively. The preform was designed for 10 layers of SiO₂-P₂O₃ doped silica (clad structure) and 5 layers of SiO₂-Al₂O₃-Er₂O₃ (core structure). Preform is analysed for the properties of layer structure i.e. refractive index profile using preform index profiler and EPMA (SEM-EDX) for dopant distribution. Results show good longitudinal uniformity despite condensation of metal organic precursor during the fabrication process. Maximum incorporation of Er₂O₃ is about 0.1 mole % with 1.5 mole% of Al₂O₃ in the core.

Abstract: Ag-Cu nanoparticles/silicate glass composites are synthesized by twice ion-exchange and reduction treatment. The as-produced glass slides were characterized by UV–Vis spectroscopy, electron probe microanalysis (EPM) and high resolution transmission electron microscopy (HRTEM). The studies show that Ag-Cu nanoparticles aggregate on the surface of the silicate glass, which size is from 2 nm to 8 nm. The copper layer on the surface of glass matrix is about 20 m by compared to Ag layer (120 m), indicating that it is more difficult for copper ions to enter into the interior. Ag-Cu migration in glass matrix cannot be simply ascribed to a direct interaction with hydrogen, but to a more complex process involving a charge balancing mechanism during hydrogen-sodium ion-exchange.

Abstract: In this work, the partial isothermal section of the Al-Ca-Zn system in the region between 33.3 and 100 at.% Ca has been investigated at 350°C using key alloys. The actual composition of the alloys is measured by inductively coupled plasma technique. Phase relations and solubility limits of the binary and ternary compounds have been determined by means of electron probe microanalysis and X-ray diffraction. In the current work, a new ternary compound has been identified in this region with the Al₉Ca₃₁Zn₁₀ (IM1) composition. Binary compound Al₁₄Ca₁₃ (IM2) has an extended solid solubility into the ternary system. The homogeneity ranges of the Al₂Ca, the MgNi₂-type C36 phase Al_2-xCaZn_x (0.28≤x≤0.70) (IM3) at 350°C and CaZn₂ compounds in the pseudobinary Al₂Ca-CaZn₂ section have been determined at 350°C and the results are combined with the literature to construct the partial vertical Al₂Ca-CaZn₂ section and partial isothermal Al-Ca-Zn section at 350°C.

Abstract: The growth mechanism of bainitic α plates in Ti-4.5Fe-6.8Mo-1.5Al, a metastable β Ti alloy, has been investigated by optical microscopy, electron probe microanalysis (EPMA) and dilatometry. The observations are compared with the transformation characteristics of primary α plates, which form at relatively high temperatures. The primary α plates form predominantly on β grain boundaries, whereas the bainitic α plates nucleate both at grain boundaries and intragranularly. It is shown that the morphological transition with decreasing temperature is associated with a change in transformation mechanism. The EPMA results show that the primary α plates are formed by a partitioning transformation. In contrast, the growth of the bainitic α plates is partitionless, followed by a post-transformation redistribution of Fe. This mechanism is similar to bainite in steel. The Fe diffusion from the supersaturated bainitic α plates to the β matrix causes the observed dilatation signal. The results of dilatometry in conjunction with optical microscopy indicate that a low misfit between the lattice structures exists, which is favourable for a partitionless transformation to occur at a low undercooling below T0.