Berlin 2012 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
MM: Fachverband Metall- und Materialphysik
MM 16: Microstructure and Phase Transformations I
MM 16.1: Vortrag
Montag, 26. März 2012, 15:45–16:00, H 1029
Deep liquid undercooling and nucleation in higher melting fcc metals — •Joachim Bokeloh, Marcel Heeger, and Gerhard Wilde — Institut für Materialphysik Münster
Since the melting enthalpy of fcc metals and therefore the driving force for crystallization scales with the melting temperature (Tm), one prediction of the classical nucleation theory (CNT) is that the onset of homogeneous nucleation for all fcc metals should be at about the same relative undercooling (ΔT/Tm). While this was initially supported by experiments by Turnbull that showed a relative undercooling in the range of 0.17 to 0.18, the homogeneous nature of the nucelation was always questioned since CNT predicts a deeper undercooling before the onset of homogeneous nucleation. In a recent publication (PRL 107, 145701), new evidence was found that the crystallization of Nickel at a relative undercooling of 0.18 is indeed caused by homogeneous nucleation. Thus, the undercoolability of several fcc metals (Au, Cu, Co, Ni) is revisited by nucleation rate measurements with an heretofore unprecedented accuracy obtained by a statistical analysis of several thousand single crystallization events. Funding by the DPG (SPP1296) is greatfully acknowleged.