2014 We study the effect of the coupling between front deformation and solutal convection on the position of the bifurcation from the planar quiescent state of a dilute binary alloy submitted to directional solidification. We set up a perturbation treatment of the coupling between the « bare » (Mullins-Sekerka and solutal convective) bifurcations. We show that the shift of the Mullins-Sekerka b...

In rapid alloy solidification the dendrite-growth velocity depends sensitively on the deviations from local interfacial equilibrium manifested by kinetic effects such as solute trapping. The dendrite tip velocityundercooling function was measured in dilute Ni~Zr! over the range 1–25 m/s and 50–255 K using electromagnetic levitation techniques and compared to theoretical predictions of the model...

We discuss the contribution of the material type in metal wires to the electromagnetic fluctuations in magnetic microtraps close to the surface of an atom chip. We show that significant reduction of the magnetic noise can be achieved by replacing the pure noble metal wires with their dilute alloys. The alloy composition provides an additional degree of freedom which enables a controlled reducti...

The elastic constants of single crystals of dilute solutions of Al, Si, Zn, Ga and Ge in Gu have been determined by the ultrasonic pulse method. Alloying causes a decrease in all the fundamental constants, C^, (C-^-C]^)^ and (G11 2C^2)/3> the relative decrease in (Gi2~Gi2)/2 being the greatest. The changes in shear constants Cu, and (C,-,-C-,2)/2 have been interpreted in terms of the known elec...

We present an approach to calculate the atomic bulk solubility in binary alloys based on the statistical-thermodynamic theory of dilute lattice gas. The model considers all the appropriate ground states of the alloy and results in a simple Arrhenius-type temperature dependence determined by a ‘‘low-solubility formation enthalpy”. This quantity, directly obtainable from first principles, is defi...

The stability of austenite against strain induced martensitic transformation (SIMT) strongly depends on the grain size of the austenite. This is observed in austenitic steels with grain sizes from several pm up to several hundred pm and for much smaller austenitic grains (three orders of magnitude) that are embedded in a non austenitic matrix. fcc Fe-precipitates may be formed in dilute Cu-Fe a...

A linear stability analysis is performed on the interface formed during the directional solidification of a dilute binary alloy in the presence of a time-periodic flow. In general, the flow is generated by translating the crystal relative to the far-field flow in elliptical orbits parallel to the interface. The presence of this complex, unsteady flow can either stabilize or destabilize the syst...

The evolution of the crystal-melt interface was investigated during directional solidification of a dilute binary alloy, starting at the marginal stability time t(i) at which the planar interface first becomes unstable. The time delay between t(i) and the crossover time t(0) at which the interface modulation becomes observable was determined experimentally. The interface morphology was analyzed...

We have investigated stress evolution in dilute nitride GaAs1−xNx alloy films grown by plasma-assisted molecular-beam epitaxy. For coherently strained films sx,2.5% d, a comparison of stresses measured via in situ wafer curvature measurements, with those determined from x-ray rocking curves using a linear interpolation of lattice parameter and elastic constants, suggests significant bowing of t...