In situ observation of ErD2 formation during D2 loading via neutron diffraction

2011 ◽  
Vol 26 (2) ◽  
pp. 144-148
Author(s):  
Mark A. Rodriguez ◽  
Clark S. Snow ◽  
Ryan R. Wixom ◽  
Anna Llobet ◽  
James F. Browning
Keyword(s):  
Solid Solution ◽  
Neutron Diffraction ◽  
Structural Changes ◽  
Solution Phase ◽  
Fluorite Phase ◽  
Solid Solution Phase ◽  
In Situ Observation ◽  
Complete Conversion ◽  
Tetrahedral Sites

In an effort to better understand the structural changes occurring during hydrogen loading of erbium target materials, we have performed in situ D2 loading of erbium metal (powder) at temperature (450°C) with simultaneous neutron diffraction analysis. This experiment tracked the conversion of Er metal to the α erbium deuteride (solid-solution) phase and then into the β (fluorite) phase. Complete conversion to ErD2.0 was accomplished at 10 Torr D2 pressure with deuterium fully occupying the tetrahedral sites in the fluorite lattice.

scholarly journals In situ observation of the tetragonal–cubic phase transition in the CeZrO4 solid solution – a high-temperature neutron diffraction study

2007 ◽  
Vol 63 (3) ◽  
pp. 384-389 ◽  
Author(s):  
Takahiro Wakita ◽  
Masatomo Yashima
Keyword(s):  
Phase Transition ◽  
Solid Solution ◽  
Neutron Diffraction ◽  
Axial Ratio ◽  
Rietveld Analysis ◽  
Atomic Displacement ◽  
Cubic Phase ◽  
In Situ Observation ◽  
Space Group

The crystal structure of the compositionally homogeneous ceria–zirconia solid solution CeZrO4 is refined by Rietveld analysis of neutron diffraction data measured in situ over the temperature range 296–1831 K. The CeZrO4 exhibits a tetragonal structure with the space group P42/nmc at temperatures from 296 to 1542 K (Z = 1), and a cubic fluorite-type form with the space group Fm\overline 3 m at 1831 K (Z = 2). The isotropic atomic displacement parameters of Ce and Zr atoms B(Ce,Zr) and O atoms B(O) are found to increase with temperature, with B(O) being larger than B(Ce,Zr), suggesting the higher diffusivity of oxygen ions. The ratio of the c axial length to the a length of the pseudo-fluorite lattice (c/a F axial ratio) for the tetragonal CeZrO4 phase increased from 296 to 1034 K and decreased from 1291 to 1542 K, reaching unity between 1542 and 1831 K. The displacement of O atoms along the c axis in the tetragonal CeZrO4 phase increased from 296 to 1034 K and decreased from 1291 to 1542 K, reaching 0.0 Å between 1542 and 1831 K. These results indicate that the cubic-to-tetragonal phase transition between 1542 and 1831 K is accompanied by oxygen displacement along the c axis and the increase of the c/a F axial ratio from unity.

Transition alpha structure in beta-isomorphous Nb-Hf alloys

1987 ◽  
Vol 45 ◽  
pp. 232-233
Author(s):  
R.W. Carpenter ◽  
Changhai Li ◽  
David J. Smith
Keyword(s):  
Solid Solution ◽  
Solution Phase ◽  
Miscibility Gap ◽  
Large Strains ◽  
Solid Solution Phase ◽  
Two Phase ◽  
Diffuse Intensity ◽  
Metastable Form ◽  
The Matrix ◽  
Equilibrium Morphology

Binary Nb-Hf alloys exhibit a wide bcc solid solution phase field at temperatures above the Hfα→ß transition (2023K) and a two phase bcc+hcp field at lower temperatures. The β solvus exhibits a small slope above about 1500K, suggesting the possible existence of a miscibility gap. An earlier investigation showed that two morphological forms of precipitate occur during the bcc→hcp transformation. The equilibrium morphology is rod-type with axes along <113> bcc. The crystallographic habit of the rod precipitate follows the Burgers relations: {110}||{0001}, <112> || <1010>. The earlier metastable form, transition α, occurs as thin discs with {100} habit. The {100} discs induce large strains in the matrix. Selected area diffraction examination of regions ∼2 microns in diameter containing many disc precipitates showed that, a diffuse intensity distribution whose symmetry resembled the distribution of equilibrium α Bragg spots was associated with the disc precipitate.

Non-equilibrium Ti-Fe bulk alloys with ultra-high strength and enhanced ductility

2004 ◽  
Vol 851 ◽  
Author(s):  
Dmitri V. Louzguine-Luzgin ◽  
Larissa V. Louzguina-Luzgina ◽  
Hidemi Kato ◽  
Akihisa Inoue
Keyword(s):  
Solid Solution ◽  
Supersaturated Solid Solution ◽  
High Strength ◽  
Eutectic Structure ◽  
Solution Phase ◽  
Solid Solution Phase ◽  
Mechanical Fracture ◽  
Glassy Alloys ◽  
Fe Alloys ◽  
Bulk Alloys

ABSTRACTThe high-strength and ductile hypo-, hyper- and eutectic Ti-Fe alloys were formed in the shape of the arc-melted ingots with the dimensions of about 25–40 mm in diameter and 10–15 mm in height. The structure of the samples consists of cubic Pm 3 m TiFe and BCC Im 3 m β-Ti supersaturated solid solution phase. The arc-melted hypereutectic Ti65Fe35 alloy has a dispersed structure consisting of the primary TiFe phase and submicron-size eutectic structure. This alloy exhibits excellent mechanical properties: a Young's modulus of 149 GPa, a high mechanical fracture strength of 2.2 GPa, a 0.2 % yield strength of 1.8 GPa and 6.7 % ductility. The hard round-shaped intermetallic TiFe phase and the supersaturated β-Ti solid solution result in a high strength of the Ti65Fe35 alloy which in addition has much higher ductility compared to that of the nanostructured or glassy alloys. The reasons for the high ductility of the hypereutectic alloy are discussed.

In situ Neutron Diffraction on DxNb2O5

1998 ◽  
Vol 53 (5-6) ◽  
pp. 557-561
Author(s):  
Tobias Unruh ◽  
Günter Schwitzgebel ◽  
Clemens Ritter
Keyword(s):  
Neutron Diffraction ◽  
Structural Changes ◽  
Electrochemical Cell ◽  
Host Lattice ◽  
Deuterium Content ◽  
Inhomogeneous Distribution ◽  
Powder Samples ◽  
Diffraction Patterns ◽  
In Situ Neutron Diffraction

Abstract DxNb2O5 is thermodynamically unstable. Therefore, neutron diffraction measurements were performed in the electrochemical cell used for the intercalation of deuterium into sintered Nb2O5 powder samples. Diffraction patterns were recorded at equilibrium potentials of -443, -428, -332 and -197 mV vs. NHE (corresponding to x = 0.232, x = 0.23, x = 0.21 and x = 0.06). The structural changes in Nb2O5 caused by the deuterium insertion are small but could be determined reproducibly. The lattice parameters of the host lattice exhibit a characteristic dependence on the deuterium content of the bronze. A model has been developed for the partially inhomogeneous distribution of the deuterium in the Nb2O5 unit cell, which explains the changes of the peak intensities observed in the low angle region (6° ≤ 2θ ≤ 18°).

Nanocrystalline Ni-30wt%Fe Supersaturated Solid Solution Synthesized by Mechanical Alloying

2014 ◽  
Vol 490-491 ◽  
pp. 38-42
Author(s):  
Yu Chen ◽  
Yang Yu ◽  
Wen Cong Zhan ◽  
Er De Wang
Keyword(s):  
Solid Solution ◽  
Crystallite Size ◽  
Powder Mixture ◽  
Supersaturated Solid Solution ◽  
Average Crystallite Size ◽  
Solution Phase ◽  
Elemental Powder ◽  
Solid Solution Alloy ◽  
Solid Solution Phase ◽  
Elemental Powder Mixture

Ni-30wt%Fe elemental power mixture was mechanically milled under argon atmosphere for variuos times up to 25h.The evolution of Ni-Fe alloying during milling and the microstructure of the as-milled powders were characterized by XRD, EPMA (electron probe microanalysis), SEM and TEM, respectively. The results show that nanocrystalline Ni (Fe) supersaturated solid solution alloy powders with 30wt. % Fe in composition can be synthesized by mechanical milling of the elemental powder mixture. Both the content of Fe dissolved and the microstrain developed in the as-synthesized Ni (Fe) solid solution phase increase, while the crystallite size decreases, steadily with increasing milling time. In particular, the Ni-30wt%Fe alloy powders obtained by 25h milling consist of a single Ni (Fe) supersaturated solid solution phase with average crystallite size of about 15nm and accumulated microstrain as high as 1.12%. DSC tests show that the nanocrystalline Ni-30wt%Fe alloy powders have a lower melting temperature than the elemental powder mixture, attributed to the unique Ni (Fe) solid solution phase structure, the nanocrystallization, and the high strain energy.

Interaction between Two Ni-Base Alloys and Ceramic Moulds

2013 ◽  
Vol 747-748 ◽  
pp. 765-771 ◽  
Author(s):  
Jian Sheng Yao ◽  
Ding Zhong Tang ◽  
Xiao Guang Liu ◽  
Cheng Bo Xiao ◽  
Xin Li ◽  
...  
Keyword(s):  
Solid Solution ◽  
Interface Reaction ◽  
Vapour Phase ◽  
Optical Microscope ◽  
Solution Phase ◽  
Solid Solution Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron ◽  
Reaction Surfaces

The interfacial reactions between ceramic moulds and DZ417G and DZ125 superalloys were investigated. The microstructure and composition of the interface region were observed by optical microscope, X-ray diffraction and scanning electron microscope with energy dispersive spectroscopy. The results showed that (Al1-xCrx)2O3solid solution phase with pink color was formed from the dissolution of Cr2O3and Al2O3and vapour phase, which was transferred to the reaction surfaces. The reaction layer thicknesses of DZ417G and DZ125 alloys were about in the range of 40-50μm. The interface reaction product between DZ417G alloy and ceramic mould was TiO2and the product between DZ125 alloy and ceramic mould was HfO2.

Sign in / Sign up

Export Citation Format

Share Document