Measured and calculated thermoelastic properties of supersaturated fcc Ni(Al) and Ni(Zr) solid solutions

1998 ◽  
Vol 13 (6) ◽  
pp. 1717-1723 ◽  
Author(s):  
J. Bøttiger ◽  
N. Karpe ◽  
J. P. Krog ◽  
A. V. Ruban
Keyword(s):  
Solid Solutions ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Lattice Constants ◽  
Thermal Expansion Coefficients ◽  
Debye Temperatures ◽  
Expansion Coefficients ◽  
Face Centered ◽  
Fcc Phase ◽  
Film Form

Metastable face-centered cubic (fcc) solid solutions of Ni1–xAlx and Ni1–xZrx have been prepared in thin-film form using dc planar magnetron sputtering in a UHV system. In both these alloy systems, extended solubilities in the fcc phase and a pronounced (111) texture are observed after sputter deposition. An amorphous phase is found to form in Ni1–xAlx for x ≥ 0.30 and in Ni1–xZrx for x ≥ 0.05. Lattice constants, thermal expansion coefficients, and Debye temperatures were derived from x-ray diffraction measurements. These parameters were also calculated by using ab initio methods in the framework of the local-spin density and coherent potential approximations for the electronic subsystem and the Debye–Grüneisen model for the vibrational properties of the nuclei subsystem. Experiment and theory are compared and discussed.

Grain Growth and Mechanical Properties of Nanograined Bulk Fe-25Ni Alloy

2005 ◽  
Vol 475-479 ◽  
pp. 3459-3462
Author(s):  
Hong Bin Wang ◽  
Xiao Yu Wang ◽  
J.H. Zhang ◽  
T.Y. Hsu
Keyword(s):  
Mechanical Properties ◽  
Grain Growth ◽  
Coarse Grained ◽  
Growth Exponent ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Ni Alloy ◽  
Face Centered ◽  
Fcc Phase

The grain growth and mechanical properties of nanograined bulk Fe-25at%Ni alloy prepared by an inert gas condensation and in-situ warm consolidation technique were investigated. About 43% high temperature face-centered-cubic (FCC) phase and 57% low temperature body-centered-cubic (BCC) phase were observed in the sample at room temperature, which was significantly different from that of the corresponding conventional coarse-grained alloy. The in-situ X-ray diffraction results show that the start and the finish temperature of BCC to FCC phase transformation are 450°C and 600°C, respectively. The isothermal grain growth exponent n from t k D D n n ¢ = − 1 0 1 for nanograined single FCC phase Fe-25at%Ni alloy is 0.38 at 750 °C . The mechanical properties changing with the grain size were studied by means of microindentation test.

In situ high-temperature X-ray diffraction characterization of silver sulfide, Ag2S

2011 ◽  
Vol 26 (2) ◽  
pp. 114-118 ◽  
Author(s):  
Thomas Blanton ◽  
Scott Misture ◽  
Narasimharao Dontula ◽  
Swavek Zdzieszynski
Keyword(s):  
High Temperature ◽  
Structure Refinement ◽  
Silver Sulfide ◽  
Rietveld Analysis ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Face Centered ◽  
Fcc Phase

Silver sulfide, Ag2S, is most commonly known as the tarnish that forms on silver surfaces due to the exposure of silver to hydrogen sulfide. The mineral acanthite is a monoclinic crystalline form of Ag2S that is stable to 176°C. Upon heating above 176°C, there is a phase conversion to a body-centered cubic (bcc) form referred to as argentite. Further heating above 586°C results in conversion of the bcc phase to a face-centered cubic (fcc) phase polymorph. Both high-temperature cubic phases are solid-state silver ion conductors. In situ high-temperature X-ray diffraction was used to better understand the polymorphs of Ag2S on heating. The existing powder diffraction file (PDF) entries for the high-temperature fcc polymorph are of questionable reliability, prompting a full Rietveld structure refinement of the bcc and fcc polymorphs. Rietveld analysis was useful to show that the silver atoms are largely disordered and can only be described by unreasonably large isotropic displacement parameters or split site models.

Studies of Microdefects, Thermal Expansion and Magnetic Properties of Fe-Ni-Co Invar Alloys

2017 ◽  
Vol 373 ◽  
pp. 146-149
Author(s):  
Wen Deng ◽  
Li Xia Li ◽  
Shou Lei Xu ◽  
Wen Chun Zhang ◽  
Yu Yang Huang ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Large Change ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Invar Alloys ◽  
Low Thermal Expansion ◽  
Expansion Coefficients ◽  
Fcc Phase ◽  
Bcc Phase

The microdefects, the thermal expansion coefficients and the magnetization -temperature curves of the Fe64Ni36-xCox (x=1~10) were characterized by means of positron lifetime, X-ray diffraction, Michelson's interferometer and VSM modular on PPMS, respectively. The Fe64Ni30Co6 alloy is a mixture of BCC and FCC structures. With the Co content increasing in Fe64Ni36-xCox alloys, the BCC phase increases, while the FCC phase decreases. In comparison with other Fe64Ni36-xCox alloys, the Fe64Ni31Co5 alloy has a rather high magnetization at temperature lower than Tc, a relatively large change of the magnetization with the temperature near Tc, and a rather low thermal expansion coefficient.

Microstructure and Homogeneity of Nanocrystalline Co–Cu Supersaturated Solid Solutions Prepared by Mechanical Alloying

1997 ◽  
Vol 12 (4) ◽  
pp. 936-946 ◽  
Author(s):  
J. Y. Huang ◽  
Y. D. Yu ◽  
Y. K. Wu ◽  
D. X. Li ◽  
H. Q. Ye
Keyword(s):  
Electron Microscopy ◽  
Mechanical Alloying ◽  
Solid Solutions ◽  
High Resolution Electron Microscopy ◽  
Face Centered Cubic ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Supersaturated Solid Solutions ◽  
Face Centered ◽  
Fcc Phase

Mechanical alloying (MA) has been performed in the CoxCu(100-x) (x = 10, 25, 50, 60, 75, and 90) system. High resolution electron microscopy (HREM) and field emission gun transmission electron microscopy (FEG TEM) were used to characterize the microstructure and homogeneity of the nanocrystalline Co25Cu75 solid solution. After 20 h of MA, all the mixtures show an entirely face-centered cubic (fcc) phase. HREM shows that the ultrafine-grained (UFG) materials prepared by MA contain a high density of defects. Two kinds of typical defects in UFG Co25Cu75 are deformation twins and dislocations. The dislocations are mostly 60° type, and in many cases they dissociate into 30° and 90° partials. The grain boundaries are ordered in structure, curved, and slightly strained, which is similar to that observed in NC–Pd. Nanoscale energy dispersive x-ray spectroscopy (EDXS) shows that the Co concentration in both the interior of grains and the GB's is close to the global composition, which proves that supersaturated solid solutions are indeed formed. In the meantime EDXS revealed that the mixing of Co and Cu in the solid solutions is homogeneous at nanometer scale. MA in the Co–Cu system is suggested to be a diffusion-controlled process, and stress-stimulated diffusion is proposed to be the reason for the formation of supersaturated solid solutions in this immiscible system.

A partly disordered 2 × 2 × 2 – superstructure of γ-brass related phase in Mn–Ni–Zn system

2021 ◽  
Vol 236 (3-4) ◽  
pp. 71-80
Author(s):  
Sivaprasad Ghanta ◽  
Anustoop Das ◽  
Rajat Kamboj ◽  
Partha P. Jana
Keyword(s):  
Crystal Structure ◽  
High Symmetry ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Cubic Lattice ◽  
The Face ◽  
Face Centered ◽  
Related Phase

Abstract The T phase in the Mn–Ni–Zn system was obtained as a product of high-temperature solid-state syntheses from the loaded composition of MnxNi2−xZn11 (x = 0.2–1.5)/MnxNi15.38−xZn84.62 (x = 1.54–11.54). The crystal structure of the T phase has been explored by means of X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS). The structures were solved in the face-centered cubic space group F 4 ‾ 3 m $F‾{4}3m$ (216) and contain 409–410 atoms/unit cell. The lattice constants were found to be a = 18.1727(2) and 18.1954(1) Å for crystals C1 and C2, respectively. The crystal structure denoted the T phase is a (2aγ)3-superstructure of the ordinary cubic γ-brass-type phase. The phase is isostructural to (Fe, Ni)Zn6.5. A “cluster” description has been used to visualize the crystal structure of the title phase. The structures have been constructed by the five distinct clusters and they are situated about the high symmetry sites of the face-centered cubic lattice. The T phase is stabilized at a valance electron concentration of 1.78, which is slightly higher than those expected for typical γ-brass Hume‐Rothery compounds.

Stability of fcc phase FeH to 137 GPa

2020 ◽  
Vol 105 (6) ◽  
pp. 917-921
Author(s):  
Chie Kato ◽  
Koichiro Umemoto ◽  
Kenji Ohta ◽  
Shoh Tagawa ◽  
Kei Hirose ◽  
...  
Keyword(s):  
High Pressure ◽  
Ab Initio ◽  
Magnetic Transition ◽  
Stability Field ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
High Pressure And Temperature ◽  
Face Centered ◽  
Fcc Phase ◽  
Fcc Structure

Abstract We examined the crystal structure of FeHX (X~1) (FeH hereafter) at high pressure and temperature by X-ray diffraction up to 137 GPa. Results show that FeH adopts a face-centered cubic (fcc) structure at pressures of 43 to 137 GPa and temperatures of ~1000 to 2000 K. Our study revises a phase diagram of stoichiometric FeH in which fcc has a wider-than-expected stability field at high pressure and temperature. Based on our findings, the FeH end-member of the Fe-FeH system is expected to be stable in the fcc structure at the P-T conditions of the Earth's core, rather than in the double-hexagonal close packed (dhcp) structure as previously reported. We compared the experimentally determined unit-cell volumes of FeH with those from ab initio calculations. Additionally, we observed a change in compressibility at ~60 GPa, which could be attributed to a magnetic transition—an interpretation supported by our ab initio computations.

scholarly journals High-pressure synthesis and thermal expansivity investigation of carbonate solid solutions Mg1-xMnxCO3

2020 ◽  
Vol 48 (4) ◽  
pp. 367-380
Author(s):  
RUI LI ◽  
WEN LIANG ◽  
HANQI HE ◽  
YONG MENG ◽  
HONGFENG TANG
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Solid Solutions ◽  
Thermal Expansivity ◽  
X Ray Diffraction ◽  
Thermal Expansion Coefficients ◽  
High Temperature Xrd ◽  
Pressure Synthesis ◽  
Expansion Coefficients ◽  
Cubic Function

Using synthesized MgCO3 and reagent-grade MnCO3 as starting materials, a series of Mg1-xMnxCO3 carbonate solid solutions were synthesized by a simple solid reaction under high-temperature-pressure conditions of 3 GPa and 800°C for 4 h. The phase compositions of as-synthesized Mg1-xMnxCO3 samples were investigated by powder X-ray diffraction (XRD); no impurities were observed. The lattice parameters were refined and showed a linear relationship as a function of the Mn2+ content, which is expected to be in accordance with the ideal solution model. Based on this, high- temperature XRD measurements were carried out to further study the thermal expansivity of Mg1-xMnxCO3. The axis thermal expansion coefficients (αa and αc) and the volumetric thermal expansion coefficient αV for Mg1-xMnxCO3 were quantified as αa =7.41×10-6/°C, αc=2.37×10-5/°C and αV=3.86×10-5/°C for x=0.0; αa =6.67×10-6/°C, αc=2.31×10-5/°C and αV=3.67×10-5/°C for x=0.1; αa=6.61×10-6/°C, αc=2.35×10-5/°C and αV=3.59×10-5/°C for x=0.3; αa=5.91×10-6/°C, αc=2.40×10-5/°C and αV=3.58×10-5/°C for x=0.5; αa=5.47×10-6/°C, αc=2.53×10-5/°C and αV=3.61×10-5/°C for x=0.7; αa=4.76×10-6/°C, αc=2.55×10-5/°C and αV=3.52×10-5/°C for x=0.9; αa=4.18×10-6/°C, αc=2.50×10-5/°C and αV=3.35×10-5/°C for x=0.3. The thermal expansion coefficients (αa, αc and αV) can be fitted with a symmetric cubic function of the Mn2+ content as αa=7.34×10-6 -7.06×10-6x+1.21×10-5x2-8.19×10-6x3; αc=2.37×10-6-7.94×10-6x+2.57×10-5x2-1.64×105x3; αV=3.85×10-5-2.08×10-5x+4.59×10-5x2-3.01×10-5x3.

Crystallographic Studies of NH4Cl—NH4Br Solid Solutions

1965 ◽  
Vol 9 ◽  
pp. 159-169 ◽  
Author(s):  
Jane Edmund Callanan ◽  
Norman O. Smith
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Solid Solutions ◽  
Room Temperature ◽  
Ammonium Bromide ◽  
Face Centered Cubic ◽  
Lattice Constants ◽  
Temperature Work ◽  
Face Centered ◽  
Slight Positive Deviation

AbstractBoth ammonium chloride and ammonium bromide undergo a transition, with rise in temperature, from an interpenetrating simple cubic (II) to a face-centered cubic (I) lattice at 183 and 137°C, respectively, and both the low- and high-temperature forms give a complete series of solid solutions. We have determined the lattice constants of the high-temperature solids at about 250° as a function of composition, and redetermined the lattice constants of the low-temperature solids at room temperature. The solutions were made by crystallization from water, followed by stirring in contact with mother liquor for at least three weeks at room temperature. Measurements were made with a Norelco- Philips diffractometer and recorder, with Cu Ko. radiation. For the high-temperature work, a simple, inexpensive heating apparatus was developed. The only previous data reported for the high-temperature forms are the lattice constants of the pure components given by Bartlett and Langmuir.The low-temperature solutions showed negative deviations from Vegard's rule at both ends of the concentration range and a slight positive deviation elsewhere when high-angle data were used. The high-temperature solutions showed marked positive deviations from Vegard's rule over the whole compositions range. Values for the pure components agreed reasonably well with those of Bartlett and Langmuir.The progress of the change II → I with time was followed for some of the solutions in the neighborhood of the transition temperature in an attempt to reveal the mechanism of the process.

Thermal Expansion Behavior of ZnSe and ZnS0.03Se0.97 Epilayers on GaAs at Temperatures in the Range, 25°C - 250°C

1994 ◽  
Vol 340 ◽  
Author(s):  
J. R. Kim ◽  
R. M. Park ◽  
K. S. Jones
Keyword(s):  
Thermal Expansion ◽  
Room Temperature ◽  
Lattice Mismatch ◽  
X Ray Diffraction ◽  
Thermal Expansion Behavior ◽  
Lattice Constants ◽  
Thermal Expansion Coefficients ◽  
Expansion Behavior ◽  
Expansion Coefficients ◽  
Lattice Matched

ABSTRACTThe thermal expansion behavior of ZnSe and ZnS0.03Se0.97 epilayers grown on GaAs has been investigated using high resolution X-ray diffraction at temperatures between room temperature and the growth temperature. The lattice parameters perpendicular and parallel to the surface were measured with the Bond's method. The lattice mismatch for a partially relaxed ZnSe layer was Δa(⊥)/a =2300 ppm and Δa(‖)/a = 2600 ppm at room temperature(R.T.) and Δa (⊥)/a =3600 ppm and Δa(‖)/a =2400 ppm at 250°C. For ZnS0.03Se0.97 which is almost lattice matched at R.T. to GaAs, Δa(⊥)/a =200 ppm, Δa(⊥)/a =20ppmatR.T. and Δa(⊥)/a =1400ppm, Δa(⊥)/a =50ppm at 250°C. The relaxed lattice constants were evaluated and the thermal expansion coefficients of relaxed ZnSe layers were found to vary from 7.8*10−6/°C at room temperature to 12.2*10−6/°C at 250°C and for ZnS0.03Se0.97 layers the variation was from 7.5*10−6/°C at R.T. to 11.7*10−6/°C at 250°C.

Metallurgical Aspects of High-palladium Alloys

1988 ◽  
Vol 67 (10) ◽  
pp. 1307-1311 ◽  
Author(s):  
P.R. Mezger ◽  
A.L.H. Stols ◽  
M.M.A. Vrijhoef ◽  
E.H. Greener
Keyword(s):  
Face Centered Cubic ◽  
Body Centered Cubic ◽  
Palladium Alloys ◽  
Secondary Phases ◽  
X Ray Diffraction ◽  
X Ray ◽  
Simple Cubic ◽  
Face Centered ◽  
Fcc Phase ◽  
Multi Phase

Nine commercial high-Pd alloys were investigated. Microstructure and phase composition were screened by x-ray diffraction, light microscopy, and an electron microprobe. After being etched, some high-Pd alloys revealed dendritic structures. The others showed a more homogeneous structure with distinct grain boundaries. Etching was necessary to reveal distinct structures, though the overall etching effect turned out to be limited. On unetched specimens, only a slight chemical heterogeneity could be determined. Except for one alloy, the systems turned out to have complex multi-phase structures. The main face-centered-cubic (fcc) phase was Pd-based. As secondary phases, body-centered-cubic (bcc) and/or simple cubic ones were detected. The latter phases were similar to a Cu3Ga and PdGa intermetallic compound, respectively. Face-centered-tetragonal (fct) structures reported by other investigators were not found.

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