Münster 1997 – wissenschaftliches Programm
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M: Metallphysik
M 7: Struktur und Umwandlungen III
M 7.1: Vortrag
Dienstag, 18. März 1997, 10:10–10:30, S 8
Time Dependent Interface Stability During Rapid Solidification — •Klaus Greven1, Andreas Ludwig1, David E. Hoglund2, and Michael J. Aziz2 — 1Gie"serei-Institut der RWTH Aachen, 52056 Aachen, Germany — 2Division of Applied Sciences, Harvard University, Cambridge, MA 02138, USA
At high solidification velocities as they occur during pulsed laser melting the planar solid- liquid interface is stabilised by capillarity and nonequilibrium effects such as solute trapping. A corresponding stability analysis has been performed by Huntley and Davis under steady state conditions. Although the velocity is found to be constant during the regrowth of the laser-melted alloy the concentration profile is in general time dependent which may cause the Huntley and Davis analysis to fail. For this work the destabilisation of a planar solid-liquid interface of Si-Sn alloys during pulsed laser-melting is investigated. Rutherford backscattering is used to determine the critical concentration for breakdown of the planar interface. The experimental data is compared with a numerical stability analysis which is performed considering the time dependent concentration profile in front of an infinitesimal perturbed planar front, as a superposition of the base state and a perturbation.Both profiles are estimated numerically. The critical concentration for breakdown is calculated as a function of velocity.