Phase Equilibria of the Nickel-Aluminium-Chromium System at 1150°C

2006 ◽  
Vol 522-523 ◽  
pp. 103-110 ◽  
Author(s):  
Yuri Kitajima ◽  
Shigenari Hayashi ◽  
Toshio Narita
Keyword(s):  
Phase Equilibria ◽  
Ternary Alloys ◽  
Diffusion Couples ◽  
X Ray Diffraction ◽  
Β Phase ◽  
Third Phase ◽  
Tie Lines ◽  
Cr System ◽  
And Diffusion

Phase equilibria in the Ni-Al-Cr system at 1150°C were investigated by using annealed ternary alloys and diffusion couples. The phase constitutions, microstructures, and tie-lines were determined by conventional techniques, including X-ray diffraction, scanning electron microscopy and electron probe microanalysis. The solubility limits of Cr was found to be about 9at.% in the γ’ and 17at.% in the β phase. The size of second or third phase precipitates in the alloys was found to affect the determination of the tie-lines by the micro probe analysis.

scholarly journals Photocatalytic Bi2O3/TiO2:N Thin Films with Enhanced Surface Area and Visible Light Activity

Coatings ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 445
Author(s):  
Luís P. Dias ◽  
Filipe C. Correia ◽  
Joana M. Ribeiro ◽  
Carlos J. Tavares
Keyword(s):  
Visible Light ◽  
Surface Area ◽  
Selective Absorption ◽  
X Ray Diffraction ◽  
Force Microscopy ◽  
Β Phase ◽  
Atomic Force ◽  
Light Activity ◽  
Vls Growth

Bi2O3 nanocone films functionalized with an overlayer of TiO2 were deposited by d.c. reactive magnetron sputtering. The aforementioned nanocone structures were formed via a vapour-liquid-solid (VLS) growth, starting from a catalytic bismuth seed layer. The resultant nanocones exhibit an improved surface area, measured by atomic force microscopy, when compared to non-VLS deposition of the same metal oxide. X-ray diffraction texture analysis enabled the determination of the crystallographic β-phase of Bi2O3. A very thin TiO2 overlayer (6 nm thick), undoped and doped with nitrogen, was deposited onto the nanocones template, in order to functionalize these structures with a photocatalytic, self-cleaning, cap material. N-doped TiO2 overlayers increased the selective absorption of visible light due to nitrogen doping in the anatase cell, thus, resulting in a concomitant increase in the overall photocatalytic efficiency.

scholarly journals Phase Equilibria in the In2O3-WO3 System

2002 ◽  
Vol 756 ◽  
Author(s):  
Annette P. Richard ◽  
Doreen D. Edwards
Keyword(s):  
Phase Equilibria ◽  
Binary Oxide ◽  
X Ray Diffraction ◽  
Subsolidus Phase ◽  
X Ray ◽  
Temperature Range ◽  
Oxide Phases ◽  
Phase Relationships

ABSTRACTThe subsolidus phase relationships in the In2O3-WO3 system at 800 – 1400°C were studied by X-ray diffraction. Two binary oxide phases – In2(WO4)3 and In6WO12 – are stable in air over the temperature range of 800 – 1200°C. Preferential volatilization of WO3 prevented the determination of phase equilibria above 1300°C.

scholarly journals III. On certain ternary alloys. Part V. Determination of various critical curves, and their tie-lines and limiting points

1892 ◽  
Vol 50 (302-307) ◽  
pp. 372-395 ◽  
Keyword(s):  
Graphical Representation ◽  
Conjugate Point ◽  
Critical Curve ◽  
Ternary Mixtures ◽  
Ternary Alloys ◽  
Conjugate Points ◽  
Critical Curves ◽  
Tie Lines ◽  
Tie Line

The triangular method of graphical representation suggested by Sir G. G. Stokes, and described in Part IV (‘Roy. Soc. Proc.,’ vol. 49, p. 174), substantially amounts to the tracing out of a curve (“ critical curve”) which shall express the saturation of the solvent C with a mixture in given variable proportions of the other two constituents, A, B ; the variation being such that any given point on the curve is related to some other point (“ conjugate point ”) in a way given by the consideration that all mixtures of the three constituents, A, B, C, represented by points lying on the line (“ tie-line ”) joining these two conjugate points (“ ideal ” alloys, or mixtures), will separate into two different ternary mixtures corresponding with the two points respectively ; whereas any mixture of the same constituents, repre­sented by a point lying outside the critical curve, will form a “ real ” alloy, or mixture, not separating spontaneously into two different fluids but existing as a stable homogeneous whole.

Microstructure and Oxidation Resistance of Cr-Ta-Si alloys

2011 ◽  
Vol 1295 ◽  
Author(s):  
Ayan Bhowmik ◽  
Hon Tong Pang ◽  
Steffen Neumeier ◽  
Howard J. Stone ◽  
Ian Edmonds
Keyword(s):  
Phase Equilibria ◽  
Oxidation Resistance ◽  
Ternary Phase Diagram ◽  
Intermetallic Phase ◽  
Ternary Alloys ◽  
Gravimetric Analysis ◽  
Silica Layer ◽  
X Ray Diffraction ◽  
Arc Melting ◽  
Si Content

ABSTRACTThe phase equilibria and oxidation resistance of alloys lying near the Cr-rich end of the Cr- Ta-Si system have been investigated. Samples were prepared by arc-melting and homogenized at 1300°C for 500hrs. Identification of the phases present and their compositions were carried out using x-ray diffraction and electron probe micro-analysis and the ternary phase diagram on the Cr-rich end was plotted. A three-phase equilibria was found to exist between an A2 Cr-solid solution, a hexagonal Laves phase and the A15 Cr3Si intermetallic phase for alloys with higher contents of Si.Thermo-gravimetric analysis of the alloys at 1100°C demonstrated an improvement in the oxidation resistance of the ternary alloys with increasing Si-content. The microstructures of the oxidized samples revealed the formation of a thick chromia layer on top of a Cr,Ta-mixed oxide layer and an internal oxidation zone for all the alloys. A protective silica layer was not observed to form in any of the alloys tested.

Influence of Quenching Rates on the Transformation of Ternary Phases in Nb-rich γ-TiAl Alloys

2011 ◽  
Vol 1295 ◽  
Author(s):  
Andreas Stark ◽  
Michael Oehring ◽  
Florian Pyczak
Keyword(s):  
Elevated Temperatures ◽  
High Energy ◽  
X Ray Diffraction ◽  
Quenching Rate ◽  
Repeated Heating ◽  
Β Phase ◽  
Third Phase ◽  
Diffusion Controlled ◽  
Temperature Ramp ◽  
Ordered Phases

ABSTRACTIntermetallic γ-TiAl based alloys with additional amounts of the ternary bcc β phase attracted increasing attention in recent years due to their improved workability at elevated temperatures. At lower temperatures the ductile high-temperature β phase can transform to several ordered phases. However, actually available phase diagrams of these multiphase alloys are quite uncertain and the precipitation kinetics of some metastable phases is far from understood.In the present study various transformations of the third phase are observed in situ by means of high-energy x-ray diffraction using synchrotron radiation. A Ti-45Al-10Nb (at.%) specimen is subject to a temperature ramp of repeated heating cycles (700 °C - 1100 °C) with subsequent quenching at different rates. Depending on the quenching rate reversible transformations of the B2-ordered βo phase to different ω related phases are observed in Ti-45Al-10Nb. At low quenching rates the hexagonal B82-ordered ωo phase is formed while at high quenching rates the metastable intermediate trigonal ω’’ phase can be preserved. The results indicate that the complete transformation from βo to hexagonal B82-ordered ωo consists of two steps which are both diffusion controlled.

Surface and Bulk Residual Stress in Ti6Al4V Welded Aerospace Tanks

2004 ◽  
Vol 126 (3) ◽  
pp. 284-292 ◽  
Author(s):  
G. Bruno ◽  
B. D. Dunn
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Neutron Diffraction ◽  
Separate Determination ◽  
X Rays ◽  
X Ray Diffraction ◽  
Β Phase ◽  
Propellant Tank ◽  
Neutron Diffraction Technique

The residual stress (RS) in two curved plates cut from a large welded propellant tank for spacecrafts was investigated nondestructively by neutron and laboratory x-ray diffraction. Each plate had two weld beads symmetric to a central monoblock reinforcement. One plate had received a post-weld heat-treatment. The two nondestructive test techniques successfully determined both the bulk (thickness averaged) and the surface stress state, due to the highly different penetration of these radiations in metals. In the as-welded tank, both neutrons and x-rays show a stress level (both in the axial and hoop directions) higher in the heat affected zone (HAZ) than in the weld pool (300 against 160 MPa). A considerable degree of relaxation annealing was observed by neutron diffraction after the application of the heat treatment. In this case, the hoop stress in the HAZ relaxes from about 300 to about 100 MPa. X-rays also permitted the separate determination of the α and β-phase stresses and the calculation of the macro-RS. The latter showed the bending deformation resulting from the cut of the plates from the original tank. The average stress measured by x-rays was found to be very similar to the RS obtained by neutron diffraction technique.

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