A neutron-diffraction study of the α phase in the palladium–gold–hydrogen and palladium–gold–deuterium systems

1968 ◽  
Vol 46 (2) ◽  
pp. 121-124 ◽  
Author(s):  
Arnulf J. Maeland
Keyword(s):  
High Temperature ◽  
Neutron Diffraction ◽  
Room Temperature ◽  
Neutron Diffraction Study ◽  
Hydrogen Atoms ◽  
Β Phase ◽  
High Temperature And Pressure ◽  
Α Phase ◽  
Die Temperature ◽  
Temperature And Pressure

It has been shown previously that both hydrogen and deuterium in β phase Pd–H and Pd–D are situated in the octahedral interstices of the f.c.c. palladium lattice, but attempts to determine the atomic positions in the α phase proved inconclusive, since only small amounts of gas are contained in this phase at room temperature. In order to locate the hydrogen atoms in the α phase by neutron diffraction the concentration must be increased. This can be accomplished by increasing die temperature and gas pressure. However, another method which avoids the use of high temperature and pressure was used in this investigation. This method is based on the observation that the addition of gold or silver to palladium results in increased hydrogen solubility in the α phase. Our neutron diffraction results on powdered α phase gold–palladium–hydrogen and gold–palladium–deuterium samples show that both hydrogen and deuterium are located in the octahedral positions of the f.c.c. metal lattice. It seems reasonable to assume that the same positions are occupied in the α phase of Pd–H.

Crystal structure of the high-pressure monoclinic phase-II of cristobalite, SiO2

2000 ◽  
Vol 64 (3) ◽  
pp. 569-576 ◽  
Author(s):  
M. T. Dove ◽  
M. S. Craig ◽  
D. A. Keen ◽  
W. G. Marshall ◽  
S. A. T. Redfern ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
High Temperature ◽  
Neutron Diffraction ◽  
Phase Ii ◽  
Monoclinic Phase ◽  
Β Phase ◽  
Α Phase ◽  
Temperature And Pressure ◽  
Pressure Phase

AbstractThe crystal structure of the high-pressure phase-II of cristobalite has been solved by neutron diffraction (space group P21/c, a = 8.3780(11) Å, b = 4.6018(6) Å, c = 9.0568(13) Å, β = 124.949(7)°, at P = 3.5 GPa). This phase corresponds to a distortion of the high-temperature cubic β-phase, rather than of the ambient temperature and pressure tetragonal α-phase.

In situ neutron diffraction study of the formation of Ho2Ge2O7 pyrochlore at high temperature and pressure

2017 ◽  
Vol 46 (44) ◽  
pp. 15415-15423 ◽  
Author(s):  
Helen Y. Playford ◽  
Craig L. Bull ◽  
Matthew G. Tucker ◽  
Nicholas P. Funnell ◽  
Christopher J. Ridley ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Neutron Diffraction ◽  
Diffraction Study ◽  
Neutron Diffraction Study ◽  
High Temperature And Pressure ◽  
Temperature And Pressure ◽  
In Situ Neutron Diffraction ◽  
High Temperature High Pressure

The formation of the spin-ice pyrochlore Ho2Ge2O7 by two different high temperature, high pressure routes has been explored using in situ neutron diffraction.

Mechanical Alloying Behavior in the Nb-Si, Ta-Si, and Nb-Ta-Si Systems

1988 ◽  
Vol 133 ◽  
Author(s):  
K. S. Kumar ◽  
S. K. Mannan
Keyword(s):  
High Temperature ◽  
Mechanical Alloying ◽  
Mechanical Milling ◽  
Room Temperature ◽  
Crystalline Compound ◽  
X Ray Diffraction ◽  
X Ray ◽  
Β Phase ◽  
Α Phase

ABSTRACTThe mechanical alloying behavior of elemental powders in the Nb-Si, Ta-Si, and Nb-Ta-Si systems was examined via X-ray diffraction. The line compounds NbSi2 and TaSi2 form as crystalline compounds rather than amorphous products, but Nb5Si3 and Ta5Si3, although chemically analogous, respond very differently to mechanical milling. The Ta5Si3 composition goes directly from elemental powders to an amorphous product, whereas Nb5Si3 forms as a crystalline compound. The Nb5Si3 compound consists of both the tetragonal room-temperature α phase (c/a = 1.8) and the tetragonal high-temperature β phase (c/a = 0.5). Substituting increasing amounts of Ta for Nb in Nb5Si3 initially stabilizes the α-Nb5Si3 structure preferentially, and subsequently inhibits the formation of a crystalline compound.

Influences of Solution Temperatures on Microstructure and Mechanical Properties of near α Titanium Alloy

2021 ◽  
Vol 1035 ◽  
pp. 89-95
Author(s):  
Chao Tan ◽  
Zi Yong Chen ◽  
Zhi Lei Xiang ◽  
Xiao Zhao Ma ◽  
Zi An Yang
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloy ◽  
High Temperature ◽  
Room Temperature ◽  
Solution Temperature ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Β Phase ◽  
Α Phase ◽  
New Type

A new type of Ti-Al-Sn-Zr-Mo-Si series high temperature titanium alloy was prepared by a water-cooled copper crucible vacuum induction melting method, and its phase transition point was determined by differential thermal analysis to be Tβ = 1017 °C. The influences of solution temperature on the microstructures and mechanical properties of the as-forged high temperature titanium alloy were studied. XRD results illustrated that the phase composition of the alloy after different heat treatments was mainly α phase and β phase. The microstructures showed that with the increase of the solution temperature, the content of the primary α phase gradually reduced, the β transformation structure increased by degrees, then, the number and size of secondary α phase increased obviously. The tensile results at room temperature (RT) illustrated that as the solution temperature increased, the strength of the alloy gradually increased, and the plasticity decreased slightly. The results of tensile test at 650 °C illustrated that the strength of the alloy enhanced with the increase of solution temperature, the plasticity decreased first and then increased, when the solution temperature increased to 1000 °C, the alloy had the best comprehensive mechanical properties, the tensile strength reached 714.01 MPa and the elongation was 8.48 %. Based on the room temperature and high temperature properties of the alloy, the best heat treatment process is finally determined as: 1000 °C/1 h/AC+650 °C/6 h/AC.

In-Situ Time-of-Flight Neutron Diffraction Study of High-Temperature α-to-β Phase Transition in Elemental Scandium

2008 ◽  
Vol 39 (12) ◽  
pp. 2815-2819 ◽  
Author(s):  
Daniel R. Kammler ◽  
Mark A. Rodriguez ◽  
Ralph G. Tissot ◽  
Donald W. Brown ◽  
Bjørn Clausen ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Neutron Diffraction ◽  
Diffraction Study ◽  
Time Of Flight ◽  
Neutron Diffraction Study ◽  
Β Phase

Second Report of the Pipe Flanges Research Committee

1939 ◽  
Vol 141 (1) ◽  
pp. 433-471 ◽  
Author(s):  
H. J. Tapsell
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Present Report ◽  
Research Committee ◽  
Packing Materials ◽  
High Temperature And Pressure ◽  
Important Addition ◽  
Temperature And Pressure ◽  
Materials Used ◽  
Bolted Flange

The research † has continued to follow the main lines of the programme originally laid down by the Committee, with an important addition, namely that relating to the study of the creep relaxation of model flanges. Some sections of the work are still incomplete; in such cases the data so far obtained are recorded and discussed, but final conclusions must be postponed until the research is terminated. The present report deals with the following sections of work:—(I) an investigation of conditions on the joint under which tightness is maintained at room temperature (p. 433); (II) an investigation of the behaviour of compressed asbestos packing materials under certain conditions of loading and temperature (p. 437); (III) the completion of the examination of the properties of the materials used in the bolt assembly tests (p. 439); (IV) experiments on full-scale bolted flange joints under conditions of high temperature and pressure (p. 441); and (V) creep relaxation tests on model flanges (p. 453).

Water Vapor Oxidation Behavior under High-Temperature and Pressure Conditions of the Nitrided Alloys for Steam Turbine Valve System Parts

2005 ◽  
Vol 475-479 ◽  
pp. 4129-4132
Author(s):  
J.H. Yoon ◽  
I.S. Kim ◽  
H.S. Kim ◽  
I.C. Hur ◽  
K.S. Son ◽  
...  
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Xrd Analysis ◽  
Corrosion Properties ◽  
High Temperature And Pressure ◽  
Nitrided Specimen ◽  
Mechanical And Corrosion Properties ◽  
Temperature And Pressure ◽  
Water Vapor Oxidation ◽  
Oxidation Behaviors

Mechanical and corrosion properties were evaluated in the nitrided and non-nitrided specimens of ASTM 355 and SUS422 steels. The oxides formed on the specimen were analyzed using by XRD and the weight change was measured after oxidation test at high temperature, high pressure, and steam conditions. The oxidation behaviors and rates between two alloys and nitrided/non-nitrided specimens were clearly different. XRD analysis showed that the nitrides formed on the nitrided specimen were composed of CrN, Fe4N, and Fe2-3N. Also, it was found that the hardness on the nitrided specimen at 283°C decreased from Hv 1150 of room temperature to Hv 425.

Sign in / Sign up

Export Citation Format

Share Document