Showing papers in "Physical Review E in 1992"

Phase-field model of solute trapping during solidification

Abstract: A phase-field model for isothermal solidification of a binary alloy is developed that includes gradient energy contributions for the phase field and for the composition field. When the gradient energy coefficient for the phase field is smaller than that for the solute field, planar steady-state solutions exhibit a reduction in the segregation predicted in the liquid phase ahead of an advancing front (solute trapping), and, in the limit of high solidification speeds, predict an alloy solidification with no redistribution of composition. Such situations are commonly observed experimentally.

Exact stopping cross section of the quantum harmonic oscillator for a penetrating point charge of arbitrary strenth

Abstract: The time-dependent Schroedinger equation for a Coulomb collision between a heavy point charge and a harmonically bound electron is solved exactly numerically. The energy transferred to the electron is studied as a function of impact parameter and projectile charge. Special attention is given to the Barkas effect and the transition from light-ion to heavy-ion stopping. The results are contrasted with classical and recent approximate results, whose precision and ranges of validity are discussed. Comparison with experimental data is made on the basis of an oscillator model of atomic stopping.