scholarly journals Determination of Phase Equilibria among δ-Fe, γ-Fe and Fe2M Phases in Fe-Cr-M (M: Hf, Ta) Ternary Systems

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 102
Author(s):  
Zhetao Yuan ◽  
Satoru Kobayashi
Keyword(s):  
Phase Equilibria ◽  
Vertical Section ◽  
Microstructural Characterization ◽  
Ternary Systems ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Cr Content ◽  
Heat Treated ◽  
Heat Resistant Steels

Phase equilibria among δ-Fe, γ-Fe, and Fe2M phases in the Fe-Cr-M (M: Hf, Ta) ternary systems were determined using bulk alloys heat-treated at high temperatures. The final goal of this study is to develop novel ferritic heat resistant steels strengthened by precipitation of Fe2M phase on the eutectoid type reaction path: δ → γ + Fe2M. The phases present in heat-treated samples were identified by microstructural characterization and X-ray diffraction pattern analysis. The chemical compositions of the phases were analyzed by energy dispersive spectroscopy. A pseudo-eutectoid trough (δ → γ + Fe2M) exists at ~1220 °C at a Hf content of 0.1% and at ~1130 °C at a Ta content of 0.6% on the vertical section at a Cr content of 9.5% in each ternary system, respectively. A thermodynamic calculation with a database that reflects reported binary phase diagrams and the present study indicates that an increase in the Cr content decreases the temperature and the Hf/Ta contents of the pseudo-eutectoid troughs. The determined phase equilibria suggest that the supersaturation of Hf/Ta for the formation of γ phase is higher in the Hf doped system than in the Ta doped system, which is probably an origin of a much slower kinetics of precipitation on the eutectoid path in the latter system.

scholarly journals Stable and Metastable Phase Equilibria Involving the Cu6Sn5 Intermetallic

2021 ◽  
Author(s):  
A. Leineweber ◽  
M. Löffler ◽  
S. Martin
Keyword(s):  
Phase Equilibria ◽  
Electron Backscatter Diffraction ◽  
Metastable Phase ◽  
Stable Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Ordered Phases ◽  
Backscatter Diffraction ◽  
Kinetics Of

Abstract Cu6Sn5 intermetallic occurs in the form of differently ordered phases η, η′ and η′′. In solder joints, this intermetallic can undergo changes in composition and the state of order without or while interacting with excess Cu and excess Sn in the system, potentially giving rise to detrimental changes in the mechanical properties of the solder. In order to study such processes in fundamental detail and to get more detailed information about the metastable and stable phase equilibria, model alloys consisting of Cu3Sn + Cu6Sn5 as well as Cu6Sn5 + Sn-rich melt were heat treated. Powder x-ray diffraction and scanning electron microscopy supplemented by electron backscatter diffraction were used to investigate the structural and microstructural changes. It was shown that Sn-poor η can increase its Sn content by Cu3Sn precipitation at grain boundaries or by uptake of Sn from the Sn-rich melt. From the kinetics of the former process at 513 K and the grain size of the η phase, we obtained an interdiffusion coefficient in η of (3 ± 1) × 10−16 m2 s−1. Comparison of this value with literature data implies that this value reflects pure volume (inter)diffusion, while Cu6Sn5 growth at low temperature is typically strongly influenced by grain-boundary diffusion. These investigations also confirm that η′′ forming below a composition-dependent transus temperature gradually enriches in Sn content, confirming that Sn-poor η′′ is metastable against decomposition into Cu3Sn and more Sn-rich η or (at lower temperatures) η′. Graphic Abstract

Estimation of Uniaxial Material Properties by Miniature Small Punch Testing to Support Post-Irradiation Examination of RPV Steels

2020 ◽  
Author(s):  
Stefan Holmström ◽  
Oliver Martin ◽  
Theo Bakker ◽  
Murthy Kolluri ◽  
Matthias Bruchhausen
Keyword(s):  
Chemical Compositions ◽  
Test Technique ◽  
Small Punch ◽  
Uniaxial Test ◽  
Heat Treated ◽  
Pressure Vessel Steels ◽  
Material State ◽  
Damaged Materials ◽  
Reactor Pressure

Abstract The small punch (SP) test technique is expected to become a more common tool for estimating tensile properties since the technique has been approved for standardization and will be published early 2020 as EN-10371. The testing technique is naturally of interest in the nuclear field due to the small amount of material needed for estimating the properties of both virgin and irradiation damaged materials. In the project STRUMAT-LTO, supported within the Sustainable Nuclear Energy Technology Platform (SNETP), there is intention to use both miniature uniaxial test specimen as well as miniature SP specimen to assess the influence of high fluence irradiation on mechanical properties of the samples of the joint NRG-JRC irradiation campaign LYRA-10. The alloys represented in the irradiation campaign are variations of VVER and PWR reactor pressure vessel steels with tailor made chemical compositions. Four of the PWR model steels are tested here with miniature uniaxial specimens using the SP technique at room temperature (RT) and 100°C in as-received material state and at RT for heat treated (450°C / 40 h) material. The SP samples were extracted from used KLST (miniature Charpy) specimens. The results of this test program are expected to provide the basis for the future development of material property determination of irradiated materials.

scholarly journals Phase Equilibria in the Nb-Rich Region of Al-Nb-Sn at 900 and 1200 °C

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2759 ◽  
Author(s):  
Ioannis Papadimitriou ◽  
Claire Utton ◽  
Panos Tsakiropoulos
Keyword(s):  
Crystal Structure ◽  
Phase Equilibria ◽  
Ternary Phase ◽  
X Ray Diffraction ◽  
High Solubility ◽  
Rich Region ◽  
X Ray ◽  
Heat Treated ◽  
Aero Engine ◽  
Scanning Electron

The Al-Nb-Sn phase diagram was studied experimentally in the Nb-rich region to provide important phase equilibria information for alloy design of Nb-silicide based materials for aero engine applications. Three alloys were produced: Nb-17Al-17Sn, Nb-33Al-13Sn and Nb-16Al-20Sn (at.%). As-cast and heat-treated alloys (900 and 1200 °C) were analysed using XRD (X-ray diffraction) and SEM/EDS (scanning electron microscopy/ electron dispersive x-ray spectroscopy). Tin showed a high solubility in Nb2Al, reaching up to 21 at.% in the Sn-rich areas, substituting for Al atoms. Tin and Al also substituted for each other in the A15 phases (Nb3Al and Nb3Sn). Tin showed limited solubility in NbAl3, not exceeding 3.6 at.% as it substituted Al atoms. The solubility of Al in NbSn2 varied from 4.8 to 6.8 at.%. A ternary phase, Nb5Sn2Al with the tI32 W5Si3 crystal structure, was found to be stable. This phase was observed in the 900 °C heat-treated samples, but not in the 1200 °C heated samples.

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.

Microstructure and Properties of Nanosemicrystalline Si3N4 Ceramics with Doped Sintering Additives: Part I. Microstructural Characterization of Nanosemicrystalline Si3N4 Powders

1998 ◽  
Vol 13 (9) ◽  
pp. 2580-2587 ◽  
Author(s):  
K. H. Ryu ◽  
J-M. Yang
Keyword(s):  
Microstructural Characterization ◽  
Degree Of Crystallinity ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sintering Additives ◽  
Transmission Electron ◽  
Wet Chemical ◽  
Si3n4 Ceramics

The characteristics of nanosized silicon nitride powders with doped Y2O3 and Al2O3 fabricated by a plasma-reacted chemical process were investigated. The chemical compositions of the powders were analyzed by wet chemical analysis. The morphology and the size distribution were determined by transmission electron microscopy (TEM). TEM with energy dispersive spectroscopy (EDS) was used to verify the existence of sintering additives in each individual particle. The crystal structure of the powders was identified by the selected area diffraction pattern (SADP). X-ray diffraction (XRD) technique was used for phase analysis and the measurement of degree of crystallinity. The characteristics of chemical bonding was analyzed by using Fourier transform infrared spectroscopy (FTIR).

Determination of Fe and Cr content in α-Zr solid solution of Zircaloy-4 with different heat-treated states

2002 ◽  
Vol 304 (2-3) ◽  
pp. 134-138 ◽  
Author(s):  
Cong Li ◽  
Bangxin Zhou ◽  
Wenjin Zhou ◽  
Pei Li ◽  
Qian Peng ◽  
...  
Keyword(s):  
Solid Solution ◽  
Cr Content ◽  
Heat Treated

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.

A microstructural characterization of Co-Zr type permanent-magnet materials

1991 ◽  
Vol 49 ◽  
pp. 782-783
Author(s):  
K. R. Lawless ◽  
G. C. Hadjipanayis
Keyword(s):  
Melt Spinning ◽  
Microstructural Characterization ◽  
X Ray Diffraction ◽  
Ion Milling ◽  
X Ray ◽  
Heat Treated ◽  
Diffraction Patterns ◽  
Rapidly Solidified ◽  
Hard Magnetic Properties

Considerable interest has been shown recently in the hard magnetic properties of Co-Zr, Co-Zr-B, and Co-Hf-B alloys, but as yet no detailed microstructural studies have been published. The Co-Zr phase diagram seems to be reasonably well known, although the crystal structure of the Co11Zr2 phase is only partially determined. This paper will report on some preliminary studies of rapidly solidified Co-Zr-B-Si and Co-Hf-B-Si alloys and binary Co-Zr alloys.All specimens used in this study were prepared by melt spinning. Specific alloys were heat treated at temperatures from 650 to 900°C. TEM specimens were prepared from ribbon material by ion milling.X-ray diffraction studies of these alloys all showed a characteristic broad peak centered around d = 0.205nm. Although it was obvious that this was a complex peak, attempts to deconvolute it were unsuccessful. SAD patterns revealed that major phases in the alloys were very heavily faulted, thus giving rise to the very confusing X-ray diffraction patterns.

scholarly journals A new approach for the determination of multiple cation locations and ordering, using the example of natural and heat-treated columbites

2011 ◽  
Vol 44 (4) ◽  
pp. 738-746 ◽  
Author(s):  
E. J. Kinast ◽  
O. Isnard ◽  
J. B. M. da Cunha ◽  
M. A. Z. de Vasconcellos ◽  
C. A. dos Santos
Keyword(s):  
Crystal Structure ◽  
Microprobe Analysis ◽  
X Ray Diffraction ◽  
Rietveld Refinements ◽  
New Approach ◽  
X Ray ◽  
Type Compound ◽  
Natural Minerals ◽  
Heat Treated

A new approach is proposed to determine unambiguously the location of four cations within the crystal structure of a naturalAB2O6columbite-type compound and derivatives, when submitted to order–disorder transitions caused by heat treatments. This method is based on the successive use of electron microprobe analysis to determine the cation concentration, Mössbauer spectroscopy to identify the Fe occupation, and a crystal structure determination of the samples combining Rietveld refinements of both neutron and X-ray diffraction. This approach is tested successfully to investigate (Fe, Mn, Nb, Ta) natural minerals as well as oxides obtained by heat treatment of the initialAB2O6columbite-type compound.

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