The effect of radiation-induced segregation on void swelling in electron-irradiated austenitic Fe-Cr-Ni-Ti-P Alloy

1990 ◽  
Vol 48 (4) ◽  
pp. 932-933
Author(s):  
H. Watanabe ◽  
T. Muroga ◽  
N. Yoshida
Keyword(s):  
Temperature Dependence ◽  
Electron Irradiation ◽  
Irradiation Temperature ◽  
The Other ◽  
Austenitic Steels ◽  
Nickel Concentration ◽  
In Situ Observation ◽  
Void Swelling ◽  
Radiation Induced

It has been reported that the void swelling in austenitic steels at higher temperatures is enhanced by a nickel depletion in matrix . The objective of the present study is to understand the effect of solute addition on void swelling, in association with microchemical changes, in austenitic steels during electron irradiation.Four types of model alloys (Fe-16Cr-17Ni, Fe-16Cr-17Ni-0.25Ti, Fe- 16Cr-17Ni-0.1P, Fe-16Cr-17Ni-0.25Ti-0.IP) and JPCA-2 were used in this study. Irradiation and in-situ observation were carried out with 1.0 MeV electrons utilizing JEM-1000 of HVEM Lab. Kyushu Univ.Fig. 1 shows the irradiation temperature dependence of nickel concentration in matrix after irradiated at 2 dpa. The ternary alloy and alloys containing phosphorus(or titanium) only show a strong nickel depletion in matrix due to nickel segregation to defect sinks. Our previous results about void swelling in these alloys showed that the temperature, where nickel depletion in matrix became prominent, corresponded to that of maxium void swelling. On the other hand, void swelling and the nickel depletion were not detected in Fe-16Cr-17Ni-0.25Ti-0.IP and JPCA-2.

scholarly journals The Effect of Bulk Composition on Swelling and Radiation-Induced Segregation in Austenitic Alloys

2000 ◽  
Vol 650 ◽  
Author(s):  
T. R. Allen ◽  
J. I. Cole ◽  
N. L. Dietz ◽  
Y. Wang ◽  
G. S. Was ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Grain Boundary ◽  
Bulk Composition ◽  
High Energy ◽  
Lattice Parameter ◽  
304 Stainless Steel ◽  
Microstructural Development ◽  
Nickel Concentration ◽  
Void Swelling ◽  
Radiation Induced

ABSTRACTChanges in bulk composition are known to affect both radiation-induced segregation and microstructural development, including void swelling in austenitic stainless steel. In this work, three alloys (designations corresponding to wt%) have been studied: Fe-18Cr-8Ni alloy (bulk composition corresponding to 304 stainless steel), Fe-18Cr-40Ni (bulk composition corresponding to 330 stainless steel), and Fe-16Cr-13Ni (bulk composition corresponding to 316 stainless steel). Following irradiation with high-energy protons, the change in hardness and microstructure (void size distribution and grain boundary composition) due to irradiation was investigated. Increasing the bulk nickel concentration decreases void swelling, increases matrix hardening, and increases grain boundary chromium depletion and nickel enrichment. The analysis shows that decreases in lattice parameter and shear modulus due to radiation- induced segregation (RIS) correlate with decreased void swelling and a decreased susceptibility to irradiation assisted stress corrosion cracking (IASCC). Traditional thinking on IASCC assumed RIS was a contributing factor to cracking. It may, however, be that properly controlled RIS can be used to mitigating cracking.

Phase Stability of Ni2Al3 under Electron Irradiation

1988 ◽  
Vol 128 ◽  
Author(s):  
E. A. Kenik ◽  
M. Nastasi
Keyword(s):  
Electron Irradiation ◽  
Phase Stability ◽  
Lattice Parameter ◽  
Low Doses ◽  
Compositional Dependence ◽  
Electron Dose ◽  
Radiation Induced ◽  
High Doses ◽  
B2 Structure

ABSTRACTIn-situ electron irradiations at 200, 300, and 1000 keV have been performed on Ni2Al3 at 100 and 300 K. At low doses, the Ni2Al3 partially disorders to a B2 structure with a lattice parameter of 0.284 nm, close to that extrapolated for β-NiAl at 60 at.% Al, the Ni2Al3 composition. The electron dose required to disorder the Ni2Al3 decreased with increasing accelerating voltage and possibly with decreasing temperature. At high doses, precipitation of aluminum from the B2 matrix occurs, along with radiation-induced sputtering and radiation-induced segregation. Lattice parameter changes for the B2 structure observed during irradiation are explained in terms of the compositional dependence of the lattice parameter of β-NiAl. The B2 structure remains stable to a dose of 6 × 1028 electrons/m2, with no amorphization detected.

In situ TEM study of irradiation-induced transformation in TiNi shape memory alloys

2003 ◽  
Vol 792 ◽  
Author(s):  
X. T. Zu ◽  
F.R. Wan ◽  
S. Zhu ◽  
L. M. Wang
Keyword(s):  
Phase Transformation ◽  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Electron Irradiation ◽  
Room Temperature ◽  
Critical Voltage ◽  
In Situ Tem ◽  
In Situ Observation

ABSTRACTTiNi shape memory alloy (SMA) has potential applications for nuclear reactors and its phase stability under irradiation is becoming an important topic. Some irradiation-induced diffusion-dependent phase transformations, such as amorphization, have been reported before. In the present work, the behavior of diffusion-independent phase transformation in TiNi SMA was studied by electron irradiation at room temperature. The effect of irradiation on the martensitic transformation of TiNi shape memory alloys was studied by Transmission Electron Microscopy (TEM) with in-situ observation and differential scanning calorimeter (DSC). The results of TEM and DSC measurements show that the microstructure of samples is R phase at room temperature. Electron irradiations were carried out using several different TEM with accelerating voltage of 200 kV, 300 kV, 400 kV and 1000 kV. Also the accelerating voltage in the same TEM was changed to investigate the critical voltage for the effect of irradiation on phase transformation. It was found that a phase transformation occurred under electron irradiation above 320 kV, but never appeared at 300 kV or lower accelerating voltage. Such phase transformation took place in a few seconds of irradiation and was independent of atom diffusion. The mechanism of Electron-irradiation-induced the martensitic transformation due to displacements of atoms from their lattice sites produced by the accelerated electrons.

In Situ Observation of Microwedge Effect on Liquid Lubrication

2004 ◽  
Vol 126 (4) ◽  
pp. 690-696 ◽  
Author(s):  
Sy-Wei Lo ◽  
Bo-Qi Zhou ◽  
Ching-Feng Fang ◽  
Yu-Sheng Lu
Keyword(s):  
Elastic Deformation ◽  
Average Velocity ◽  
Contact Region ◽  
Hydrodynamic Pressure ◽  
The Other ◽  
In Situ Observation ◽  
Sliding Velocity ◽  
Surface Separation ◽  
Tool Surface

The influence of the minute elastic deformation of tool surface, named the “microwedge,” on the asperity crushing in liquid lubrication is investigated experimentally. The microwedge plays a role so dominant that although increasing the average velocity of the lubricant can alleviate the asperity deformation; such efforts will be overwhelmed by the microwedge effect if the relative sliding velocity between tool and workpiece is also enhanced concurrently. For all roughness patterns, the asperities show multidirectional expansions of the contact region; an important feature of the microwedge effect. The microwedge effect also creates distributions of surface separation and hydrodynamic pressure neither expected nor explainable by the other models.

scholarly journals Patterns of sarcomere activation, temperature dependence, and effect of ryanodine in chemically skinned cardiac fibers.

1986 ◽  
Vol 87 (6) ◽  
pp. 885-905 ◽  
Author(s):  
A Lundblad ◽  
H Gonzalez-Serratos ◽  
G Inesi ◽  
J Swanson ◽  
P Paolini
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Temperature Dependence ◽  
Calcium Release ◽  
Contractile Activity ◽  
The Other ◽  
Calcium Blockers ◽  
Calcium Accumulation ◽  
Contractile Activation

Functionally skinned and electrochemically shunted myocytes were prepared by perfusing rat hearts with collagenase in order to obtain a technically improved measurement of sarcomere dynamics and to evaluate the role of sarcoplasmic reticulum in situ with respect to contractile activation. In the presence of micromolar calcium, the myocytes exhibited phasic and propagated contraction waves beginning at one end and proceeding along the myocyte. Beating rates, the propagation velocity of the activation wave, and single sarcomere shortening and relaxation velocities were obtained by manual or automated analysis of 16-mm film recorded at 170 frames/s from a camera attached to a microscope that was equipped with a temperature-controlled stage. In parallel experiments, calcium accumulation by the sarcoplasmic reticulum of the myocytes in situ was measured by direct isotopic tracer methods. The frequency (10-38 min-1) of spontaneous contractions, the velocity (1.9-7.4 microns . s-1) of sarcomere shortening, and the velocity (1.7-6.8 microns . s-1) of sarcomere relaxation displayed identical temperature dependences (Q10 = 2.2), which are similar to that of the calcium pump of sarcoplasmic reticulum and are consistent with a rate limit imposed by enzyme-catalyzed mechanisms on all these parameters. On the other hand, the velocity (77-159 microns . s-1) of sequential sarcomere activation displayed a lower temperature dependence (Q10 = 1.5), which is consistent with a diffusion-limited and self-propagating release of calcium from one sarcomere to the other. The phasic contractile activity of the dissociated myocytes was inhibited by 10(-8)-10(6) M ryanodine (and not by myolemmal calcium blockers) under conditions in which calcium accumulation by sarcoplasmic reticulum in situ was demonstrated to proceed optimally. The effect of ryanodine is attributed to an interaction of this drug with sarcotubular structures, producing inhibition of calcium release from the sarcoplasmic reticulum. The consequent lack of sarcomere activation underlines the role of sarcoplasmic reticulum uptake and release in the phasic contractile activation of the electrochemically shunted myocytes.

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