Microstructural stability of the Kirkendall plane in solid-state diffusion

In a diffusion-controlled interaction, the Kirkendall plane, as marked by inert particles placed at the original contact surface of a reaction couple, need not be unique. Multiple planes can develop, and sometimes the Kirkendall plane does not exist at all. A phenomenological approach is introduced to rationalize the Kirkendall-effect-mediated migration of macroscopic inclusions inside a diffusion zone.     

Measuring deuteron beam parameters with solid-state track detectors in experiments with the QUINTA target assembly

The results of measurements of the beam parameters on the target upon irradiation of the QUINTA subcritical uranium assembly with deuterons with energies of 1, 4, and 8 GeV are presented. Data on the position of the incident particle beam relative to the assembly axis and on the actual geometric parameters of the beam make it possible to analyze information on the spatial distributions of reaction rates within the target assembly correctly, comparing such distributions obtained at different irradiation sessions and modeling the experiments with the use of MCNPX, GEANT4, FLUKA, and other similar software tools.     

Flux-driven cellular precipitation in open system to form porous Cu3Sn

Recently, a new morphology of porous Cu₃Sn with lamellar structure is observed. Several possible explanations of the formation are proposed and compared. The most reasonable one seems to be the one based on a theory of flux-driven cellular precipitation in open system. Outflux of Sn from Cu₆Sn₅ generates simultaneously supersaturation with vacancies and with copper leading to the eutectoid-like transformation β → α + γ (where γ is void). The transformation is complete due to a complete outflux of Sn from the Cu₆Sn₅ phase. Simple formulae for prediction of the lamellar structure parameters and the propagation velocity are obtained and compared reasonably with experimental data. The suggested model can be interpreted as one more case of the flux-driven phase transformations in open systems.     

Ripening with noise

The process of ripening has been considered taking into account the noise from different sources, namely the scatter of compositions (supersaturation Δ) in the vicinity of precipitates and scatter of the Gibbs–Thompson term α. The evolution of the particle size distribution (PSD) has been investigated using parameters that characterize the width, sharpness and slope of the peak. Accounting for noise in our model produces a PSD that is closer to the experimental data compared with LSW theory.     

Space-charge gratings in photorefractive crystals controlled by an external variable electric field

Specific features of space-charge gratings excited in photorefractive crystals in the presence of an external variable electric field that exhibits power-law time dependence are studied. It is demonstrated that the process under study substantially depends on a parameter of an increase in the external electric field over a time interval that corresponds to the generation of space-charge gratings in the absence of the field. At a relatively small parameter, the charge can be increased in accordance with variations in the field, charge oscillations with increasing amplitude can be induced, and identical excitation of the gratings can be maintained. At a relatively large parameter, the charge of the gratings is proportional to the time of external action, so that the charge can be controlled using external variable electric field.