scholarly journals The Effect of Temperature and Mo Content on the Lattice Misfit of Model Ni-Based Superalloys

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 700 ◽  
Author(s):  
Amy J. Goodfellow ◽  
Lewis R. Owen ◽  
Katerina A. Christofidou ◽  
Joe Kelleher ◽  
Mark C. Hardy ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Room Temperature ◽  
Lattice Misfit ◽  
Lattice Parameter ◽  
Lattice Parameters ◽  
Effect Of Temperature ◽  
General Decrease ◽  
Mo Content ◽  
Increasing Temperature ◽  
Mo Additions

The lattice parameters and misfit of the γ and γ′ phases in a series of model quaternary Ni-based superalloys with and without Mo additions have been determined using neutron diffraction between room temperature and 700 °C. Despite the fact that Mo is typically expected to partition almost exclusively to the γ phase and thereby increase the lattice parameter of that phase alone, the lattice parameters of both the γ and γ′ phases were observed to increase with Mo addition. Nevertheless, the effect on the γ lattice parameter was more pronounced, leading to an overall decrease in the lattice misfit with increasing Mo content. Alloys with the lowest Mo content were found to be positively misfitting, whilst additions of 5 at.% Mo produced a negative lattice misfit. A general decrease in the lattice misfit with increasing temperature was also observed.

Structural Properties and Stability of Metastable Phases in the Zr-Nb System

2005 ◽  
Vol 480-481 ◽  
pp. 565-572 ◽  
Author(s):  
G. Aurelio ◽  
A. Fernández Guillermet ◽  
G.J. Cuello ◽  
P.B. Bozzano
Keyword(s):  
Neutron Diffraction ◽  
Structural Properties ◽  
Room Temperature ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Lattice Parameters ◽  
Effect Of Temperature ◽  
Neutron Diffraction Data ◽  
Temperature Changes ◽  
Vegard’S Law

The lattice parameters of the bcc (b) and omega (W) phases occurring metastably in a series of Zr-rich Zr-Nb alloys have been determined at and above room temperature (TR) using neutron diffraction techniques. In the first place, the effect of temperature changes upon the lattice parameters of the b and W phases in alloys with 10 and 18 at.% Nb was monitored using neutron thermodiffraction. A method of analysis is applied to the data which involves a confrontation between the observed structural properties and an idealised -or ``reference'- behaviour (RB) which admits a simple mathematical description. A generalised form of Vegard's law is adopted as RB for the b phase, whereas a specific RB is proposed for the W structure. The experimental data are well accounted for by this interpretation scheme, leading to a picture of the isothermal reactions occurring at high temperature which involves the transfer of Nb from the W to the b phase. Finally, the neutron diffraction data on the W phase are combined with an electron microscopy study for the alloy with 10 at.% Nb aged at 773 K, which provides information on the composition of this phase and its evolution towards thermodynamic equilibrium.

Effect of Temperature on Crater Formation and Ejecta Composition in Aluminum Alloy Targets

2012 ◽  
Vol 706-709 ◽  
pp. 768-773
Author(s):  
Masahiro Nishida ◽  
Koichi Hayashi ◽  
Junichi Nakagawa ◽  
Yoshitaka Ito
Keyword(s):  
Aluminum Alloy ◽  
High Temperature ◽  
Low Temperature ◽  
Room Temperature ◽  
Effect Of Temperature ◽  
Crater Formation ◽  
Influence Of Temperature ◽  
Gas Gun ◽  
Influence Of Temperature On ◽  
Increasing Temperature

The influence of temperature on crater formation and ejecta composition in thick aluminum alloy targets were investigated for impact velocities ranging from approximately 1.5 to 3.5 km/s using a two-stage light-gas gun. The diameter and depth of the crater increased with increasing temperature. The ejecta size at low temperature was slightly smaller than that at high temperature and room temperature. Temperature did not affect the size ratio of ejecta. The scatter diameter of the ejecta at high temperature was slightly smaller than those at low and room temperatures.

The Deformation Microstructure in NI3Si Polycrystals Strained Over the Range of Temperature of Flow Stress Anomaly

1988 ◽  
Vol 133 ◽  
Author(s):  
B. Tounsia ◽  
P. Beauchamp ◽  
Y. Mishima ◽  
T. Suzuki ◽  
P. Veysslière
Keyword(s):  
Flow Stress ◽  
Slip System ◽  
Room Temperature ◽  
Peak Temperature ◽  
Effect Of Temperature ◽  
Screw Dislocations ◽  
Thermally Activated ◽  
Cube Plane ◽  
Octahedral Slip ◽  
Increasing Temperature

ABSTRACTIn order to correlate the flow stress anomaly of Ni3Si with dislocation properties, a weakbeam study ofpolycrystalline samples deformed between ambient and the peak temperature was carried out. Samples with two extreme Ni/Si ratios were tested.The most frequently activated slip system changes progressively from octahedral to cubic with increasing temperature. The transformation of superdislocations into Kear-Wilsdorf configurations gives rise to screw dislocations that are rectilinear only after deformation at room temperature. The effect of temperature is to gradually promote bending of Kear-Wisdorf configurations in the cube plane, from a few nanometers at 230°C to several tenths of micrometers at intermediate temperature. Cube slip begins to be massively activated a little below the peak temperature. It is suggested that the flow stress anomaly is controlled by progressive exhaustion of octahedral slip by thermally-activated expansion of superdislocations on the cube cross-slip plane.

Effect of Temperature and Strain Rate on the Mechanical Properties of 99.5 Aluminium Rods Extruded by KOBO

2016 ◽  
Vol 879 ◽  
pp. 230-235
Author(s):  
Sonia Boczkal ◽  
Marzena Lech-Grega ◽  
Wojciech Szymanski ◽  
Paweł Ostachowski ◽  
Marek Lagoda
Keyword(s):  
Strain Rate ◽  
Room Temperature ◽  
High Strain ◽  
Effect Of Temperature ◽  
Recrystallization Process ◽  
Extrusion Force ◽  
Strain Rates ◽  
High Strain Rates ◽  
Constant Frequency ◽  
Increasing Temperature

In this study, aluminium rods were cold extruded in a direct process by KOBO method in two variants: variant I with varying (decreasing) frequency of die oscillations necessary to maintain a constant extrusion force, and variant II with constant frequency of die oscillations, leading to a decrease in the extrusion force. The tensile test of rods was carried out in a temperature range of 20 - 200°C and at a strain rate from 8xE10-5 to 8xE10-1 s-1. Significant differences in the elongation of the tested rods were observed. It was found that rods extruded at variable die oscillations and stretched at room temperature had similar elongation, independent of the strain rate. With the increase of temperature, the elongation of samples stretched at a low speed was growing from a value of about 8% at room temperature up to 40% at 200°C. At high strain rates, despite the increasing temperature, the elongation remained at the same level, i.e. 5-6%. In rods extruded at constant die oscillations, the elongation at a low strain rate was growing with the temperature from 10% at room temperature up to 29% at 200°C. At high strain rates, the elongation decreased from 28% at room temperature to 11% at 200°C. The results were interrelated with examinations of the structure of rods and fractures of tensile specimens. In the material extruded by KOBO method with constant die oscillations, the beginnings of the recrystallization process were observed, absent in the material extruded at variable die oscillations.

The Effect of Temperature on the Material Damping of Graphite/Epoxy Composites in a Simulated Space Environment

1990 ◽  
Vol 112 (3) ◽  
pp. 277-279 ◽  
Author(s):  
G. T. Spirnak ◽  
J. R. Vinson
Keyword(s):  
Room Temperature ◽  
Damping Ratio ◽  
Theoretical Models ◽  
Space Environment ◽  
Effect Of Temperature ◽  
Time Cost ◽  
Material Damping ◽  
Temperature Dependent ◽  
Increasing Temperature ◽  
Free Beam

An experimental method for measuring material damping is described, which employs a free-free beam lightly supported at the nodes. A thermal space environment is simulated by measuring the material damping in air at temperatures ranging from −65°F to 225°F, and then subtracting out the effects of atmospheric damping. This method saves considerable time, cost and experimental difficulties associated with performing the experiments in a vacuum. Graphite/epoxy AS4/3501-6 composite beam specimens were tested. At room temperature, the [0°]12 composites were found to have an average damping ratio of 0.0556 percent. The [90°]12 composites were found to have an average material damping ratio of 0.55 percent. These data agree well with the theoretical models and experimental measurements performed in a vacuum. The material damping ratio is temperature dependent over the range −65°F to 225°F, increasing with increasing temperature. For the [0°]12 composite, the material damping ratio varies from 0.0397 percent at −65°F to 0.083 percent at 225°F. For the [90°]12 composite, the material damping ratio varies from 0.408 percent at −65°F to 0.860 percent at 225°F.

Infrared spectra of the ammonium ion in crystals. Part VII. Existence of symmetrically trifurcated hydrogen bond in ammonium halides

1980 ◽  
Vol 58 (3) ◽  
pp. 270-282 ◽  
Author(s):  
Osvald Knop ◽  
Wolfgang J. Westerhaus ◽  
Michael Falk
Keyword(s):  
Room Temperature ◽  
Ammonium Ion ◽  
Effect Of Temperature ◽  
Hydrogen Bonding Interaction ◽  
Maximum Probability ◽  
Threefold Axis ◽  
Ammonium Halides ◽  
Bonding Interaction ◽  
Increasing Temperature

This investigation deals with the effect of temperature, between 10 and 293 K, on the ir spectrum of the NH3D+ probe ion in polycrystalline NH4SnF3, NH4CuSO3, cubic (NH4)2SiF6, and (NH4)2SnCl6. The results lead to the following conclusions. At 10 K these crystals contain symmetrically trifurcated [Formula: see text] bonds, i.e. bonds in which the N—H orientation of maximum probability is on the threefold axis. With increasing temperature these bonds lose progressively their symmetrically-trifurcated character to become highly bent, highly dynamic [Formula: see text]•bonds, and the strength of the hydrogen-bonding interaction increases. This is reflected in the decrease of the ND stretching frequency of the probe ion with increasing temperature, which is the opposite of the behaviour observed with normal (i.e. essentially straight) [Formula: see text] bonds.Re-determination of the room-temperature crystal structure of NH4CuSO3 has confirmed the correctness of the structure reported previously by Nyberg and Kierkegaard.

A Comparison of X-Ray and Neutron Diffraction Measurement of Lattice Parameters for the Determination of Residual Stress and Chemical Composition in Zirconium Alloy Tubes

1991 ◽  
Vol 35 (A) ◽  
pp. 475-480
Author(s):  
M. Griffiths ◽  
J.E. Winegar ◽  
J.F. Mecke ◽  
T.M. Holden ◽  
R.A. Holt
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Zirconium Alloys ◽  
Lattice Parameter ◽  
Lattice Parameters ◽  
Surface Relaxation ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
X Ray

AbstractIntergranular residual stresses can exist in zirconium alloys, especially when there is a large distribution of grain orientations. The stresses result from the anisotropic plasticity and thermal expansion of the hexagonal close-packed crystal structure of α-zirconium. Apart from complicating the characterisation of materials using lattice parameter measurements, the intergranular stresses can significantly affect material behaviour, especially in nuclear reactor environments, and there is therefore a great deal of interest in their measurement.The effects of specimen preparation and surface relaxation on X-ray diffraction measurements of lattice parameters of zirconium alloys have been investigated by comparing bulk neutron diffraction with X-ray diffraction on identical materials. The results show that: (i) intergranular or interphase residual stresses exist in dual-phase Zr-2.5Nb pressure tubes; (ii) the stresses normal to the surface of an X-ray diffraction specimen are not relieved completely when there are intergranular residual stresses in the material. One can conclude that intergranular stresses have to be considered when determining chemical compositions from lattice parameter measurements and also when measuring macroscopic residual stress using X-ray diffraction.

Precise Lattice Parameters of the Sr0.61Ba0.39Nb2O6 Single Crystal

2007 ◽  
Vol 130 ◽  
pp. 73-76 ◽  
Author(s):  
Paweł Pacek ◽  
Krystyna Wokulska ◽  
Jan Dec ◽  
Tadeusz Łukasiewicz
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Room Temperature ◽  
Czochralski Method ◽  
Lattice Parameter ◽  
Lattice Parameters ◽  
Space Group

Single crystals of composition Sr0.61Ba0.39Nb2O6 (space group P4bm) were prepared using the Czochralski method. The Bond's method of the precise lattice parameter measurements was used to study structure of SBN 61 at room temperature. In this way lattice parameters a = b = 12.45676 ± 6*10-5Å and c = 3.93541 ± 5*10-5Å were determined.

Synthesis and Electrical Properties of Mo-ZrO2 Cermet

2011 ◽  
Vol 311-313 ◽  
pp. 2121-2126
Author(s):  
Ji Fang Xu ◽  
Gong Yuan Liu ◽  
Lei Tang ◽  
Jie Yu Zhang ◽  
Chang Jie
Keyword(s):  
Electrical Conductivity ◽  
High Temperature ◽  
Electrical Properties ◽  
Room Temperature ◽  
Optical Microscope ◽  
Metal Phase ◽  
Phase Zone ◽  
Ceramic Phase ◽  
Mo Content ◽  
Increasing Temperature

Under the protected condition of the purified argon atmosphere, Mo-ZrO2cermets were sintered by Mo powder and ZrO2powder at 1873K for 2 hours. Mircostructure of cermets were observed by means of XRD, optical microscope and SEM anslysis. Electrical properties of sintered samples with different Mo content and temperature were measured using DC four-electrode method. The results showed that metal phase and ceramic phase were independent of each other. With the reduction of Mo content, Mo metal phase as the continuous network structure is dispersedly distributed in the ceramic phase zone. The electrical conductivity of cermets at room temperature increased with decreaseing of the Mo content. The trend that the high-temperature electrical conductivity of cermets changed with the Mo content is the same as the trend that at the room temperature. When the Mo content is greater than 40%, the high-temperature electrical conductivity increased linearly with increasing temperature. The electrical conductivity of 40mol-% Mo-ZrO2reached the peak at 1223K and 1473K.

Phase Transitions in Al87Ni7Nd6

2003 ◽  
Vol 806 ◽  
Author(s):  
Despina Louca ◽  
K. Ahn ◽  
A. K. Soper ◽  
S. J. Poon ◽  
G. J. Shiflet
Keyword(s):  
Phase Transitions ◽  
Neutron Diffraction ◽  
Metallic Glass ◽  
Atomic Structure ◽  
Crystalline Phase ◽  
Room Temperature ◽  
Local Environment ◽  
Pair Density ◽  
Pdf Analysis ◽  
Increasing Temperature

ABSTRACTThe local atomic structure of Al87Ni7Nd6 amorphous metallic glass was determined upon heating by neutron diffraction and the pair density function (PDF) analysis. Two isotopes of Ni with very different scattering intensities were used (58Ni and 60Ni) to separate the local environment of the transition metal. A distinct pre-peak observed in reciprocal space arises because of chemical clustering of Ni atoms. With increasing temperature the coherence length of this peak increases indicating an enhancement in atomic clustering. In addition, precipitation of Al metal is first observed at 200 °C with heating. Binary and ternary Al phases form as the temperature increases further to 500 °C although the majority crystalline phase is Al. The local atomic topology at the intermediate temperatures can be represented with a model that is a combination of the atomic structure at room temperature plus Al.

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