Initial transient behavior in directional solidification of a bulk transparent model alloy in a cylinder

Abstract

International audienc

Experimental observation of oscillatory cellular patterns in three-dimensional directional solidification

“…This range is relatively close to the critical velocity Vc, corresponding to the transition from planar to cellular fronts, which is equal to 0.25 µm/s for G1, and 0.16 µm/s for G2 [40,45]. The oscillation modes are bounded in the velocity range 2 < V/Vc < 6, which is in good agreement with the results obtained for thin samples at V/Vc ≃ 4.5 [28].…”

“…Two different sets of control temperatures were used that correspond to two different thermal gradients, estimated by thermal numerical simulation at G1 = 19 K/cm and G2 = 12 K/cm. A more complete discussion of the thermal gradient determination can be found in [40]. A range of pulling velocities from 0.25 to 30 µm/s was studied which covers a range of microstructures from planar to cellular and dendritic.…”

“…solute diffusion coefficient, interfacial anisotropy, or temperature gradient). Several of those parameters have thus been reassessed (thermal gradient G [40]) and remeasured (partition coefficient k in [45]). However, the revised values have not up to now enabled us to resolve the discrepancy between simulated and observed spacings.…”

Three-Dimensional Multiscale Modeling of Dendritic Spacing Selection During Al-Si Directional Solidification

“…34 Other possible sources of discrepancy between simulations and experiments include: the limited sample size of the measurements (e.g., only two spacings in Fig. 2), solutal convection (observed in Al-Cu thin samples 45 ), the development of a solute boundary layer during the thermal stabilization of the melted sample, 46 the thermal inertia of the setup at the initiation of cooling, 47 as well as uncertainties in materials parameters and processing conditions. Interestingly, spacing selection after planar destabilization and cross-section widening yielded similar spacings, unlike in 2D where both DNN 15 and phase-field 16 systematically predict larger spacings from branching than from planar destabilization.…”

In situ observation the interface undercooling of freezing colloidal suspensions with differential visualization method

“…three different factors 26 : 1. An isotherm shift due to pulling that is deduced from the comparison of the liquidus isotherms positions at rest and during pulling for H = 0; this shift of isotherms can be seen as the "instrumental recoil", which is due to the evolution of thermal exchanges induced by pulling; 2.…”