Showing papers on "Critical radius published in 1992"
TL;DR: The critical radius for dissolution is found to increase with solute content inside the spinodal thus leading to full dissolution of one of the components.
Abstract: We report on the formation by mechanical alloying of fcc solid solution of Fe and Cu, which are immiscible. Intense codeformation of Cu with Fe and other high-melting bcc metals generates small fragments with tip radii of the order 1 nm such that capillary pressures force the atoms on these fragments to dissolve. The critical radius for dissolution is found to increase with solute content inside the spinodal thus leading to full dissolution of one of the components. The fcc-FeCu solid solutions have Curie temperatures similar to those of vapor-deposited alloys and a positive heat of mixing that is in accord with theoretical results.
414 citations
TL;DR: In this paper, central concepts derived from theory, including the critical radius and critical number of gas atoms, cavity-precipitate interactions, and relative sink strengths for point defects, are applied to the interpretation of experimental data.
Abstract: Austenitic Fe-Cr-Ni steels are potential candidate alloys for structural materials in both fast breeder and magnetic fusion reactors. However, void swelling and phase instability during irradiation have been major problems limiting the properties and useful lifetimes of these materials and thus have been the subject of intensive investigations. Cavity nucleation in steels subjected to displacement damage is strongly influenced by the interactions between helium atoms and precipitates which are formed during irradiation. Several important mechanisms regarding gas atom-precipitate interactions and principles for the design of radiation-resistant alloys are critically examined. Central concepts derived from theory, including the critical radius and critical number of gas atoms, cavity-precipitate interactions, and relative sink strengths for point defects, are applied to the interpretation of experimental data.
35 citations
TL;DR: In this paper, the flow of water through a porous medium is simulated numerically using a cubic network of cylindrical capillary tubes as the conceptual model of the medium, and Poiseuille's law is used to relate the viscous dissipation within the fluid to the pressure gradient driving the flow.
Abstract: The flow of water through a porous medium is simulated numerically using a cubic network of cylindrical capillary tubes as the conceptual model of the medium. Poiseuille's law is used to relate the viscous dissipation within the fluid to the pressure gradient driving the flow. The pore size distribution is determined from the capillary pressure function of the medium, and the tubes are randomly arranged within the network. A critical pore radius is identified as the limiting pore size which contributes to the permeability structure of the medium. When only tubes from that part of the pore size distribution above this critical radius are used to form the network, the permeability of the network equals the measured permeability of the medium. This parameter, the critical pore radius, links the permeability to the pore size distribution and gives insight into the topological structure of the medium.
34 citations
27 citations
TL;DR: In this paper, the authors studied the mechanism and the criteria of unstable behavior of wave fronts in the Ce-catalyzed Belousov-Zhabotinsky reaction and the transition from stable to unstable behavior was followed by measuring several properties (velocity, spiral wavelength, width of the autocatalyst band, critical radius, transition time of instability).
23 citations
TL;DR: In this paper, the authors measured the spreading of PDMS oils on flat oxidized silicon wafers and determined the complete drop profile for droplet radii larger than the capillary length, defined by κ − 1 = ( γ ρg ) 1 2, where γ is the surface tension of the liquid, ρ its density, and g the gravitational acceleration.
19 citations
01 Jan 1992
TL;DR: In this paper, a predictive model for moisture induced void formation and growth is presented, which incorporates a one-dimensional sub-model for the desorption of moisture and the variation of diffusivity with temperature.
Abstract: A predictive model for moisture induced void formation and growth is presented. This model incorporates a one-dimensional sub-model for the desorption of moisture. The variation of diffusivity with temperature is accounted for in this sub-model, which shows that high heating rates do not allow sufficient time for desorption of moisture from the thermoplastic polymer/matrix. Thus, significant amounts of moisture are still present within the polymer, facilitating void nucleation at elevated temperatures. The moisture concentration profile obtained from this sub-model is coupled with classical nucleation theory, to enable prediction of whether moisture related voids will be nucleated as a function of the initial moisture profile in the material, the process temperature, applied pressure and the heating rate. If conditions for moisture related void nucleation are satisfied, the spatial location of the void within the polymer/matrix and the critical radius of the void nucleus are used in a void growth sub-model to track the growth of the voids as a function of the process conditions and time, thus giving the final void content of the part.
12 citations
TL;DR: Fe15Cr-xNi alloys irradiated at both low (0.66 to 1.2) and very high (27 to 58) helium/dpa levels exhibit significantly different levels of strengthening due to an unprecedented refinement of cavity microstructure at the very high helium levels as mentioned in this paper.
9 citations
TL;DR: The kinetics of domain growth associated with a first-order phase transition is studied and exact solutions of one-dimensional growth models with nonzero critical radius of nucleation are obtained.
Abstract: We study the kinetics of domain growth associated with a first-order phase transition. Exact solutions of one-dimensional growth models with nonzero critical radius of nucleation are obtained and compared with approximate results.
6 citations
Patent•
20 May 1992
TL;DR: In this paper, the authors proposed a strain transducer for a laminated composite structure, such as a component of an aircraft wing, where the optical fiber is disposed within a plane and the detectable loss is greater for an out-of-plane deflection than for an in-plane defect.
Abstract: A strain transducer (14) is responsive to a deflection thereof for providing a detectable output signal having a characteristic that is expressive of the deflection. The transducer includes an optical fiber having an input port (16) for coupling to a source (18) of optical radiation and an output port (20) for coupling to a receiver (22) of the optical radiation. The optical fiber has at least one region (14') that has a radius of curvature that is equal to or less than a critical radius of curvature for the optical fiber. The at least one region includes a detectable loss in the optical signal in response to being deflected. The optical fiber is disposed within a plane and the detectable loss is shown to be greater for an out-of-plane deflection than for an in-plane deflection. The strain transducer is shown to be especially useful for inclusion within a laminated composite structure, such as a component of an aircraft wing.
4 citations
TL;DR: In this paper, the evolution of bubbles with arbitrary initial density in an infinite nuclear system is studied including kinetic-pressure fluctuations on the bubble surface, and the critical radius and probability for bubble expansion are found to depend significantly upon both the initial bubble density and the nuclear equation of state.
Abstract: The evolution of bubbles with arbitrary initial density in an infinite nuclear system is studied including kinetic-pressure fluctuations on the bubble surface. The critical radius and probability for bubble expansion are found to depend significantly upon both the initial bubble density and the nuclear equation of state.
TL;DR: In this article, the variation of the critical radius in the monoenergetic-neutron transport theory has been studied and the FN method is used to solve the critical problem, for the case of specified isotropic scattering.
Abstract: In this article, the variation of the critical radius in the monoenergetic-neutron transport theory has been studied. TheFN method is used to solve the critical problem, for the case of specified isotropic scattering. Exact numerical results are obtained and tabulated for selected illustrative cases. The results indicate that the critical radius increases with increasing forward anisotropic scattering.