Regensburg 2007 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 29: Intermetallic phases II
MM 29.4: Talk
Thursday, March 29, 2007, 12:30–12:45, H16
Non-equilibrium solidification of intermetallic phases in Ni-Al and Ti-Al alloy systems — •Helena Hartmann1,2, Peter Galenko2, Hamid Assadi3, Sven Reutzel1,2, Roman Lengsdorf1,2, and Dieter Herlach2 — 1Institut für Experimentalphysik IV, Ruhr-Universität, 44780 Bochum, Germany — 2Institut für Materialphysik im Weltraum, DLR, 51170 Köln, Germany — 3Tarbiat Modarres University, Tehran, Iran
Rapid solidification of intermetallic alloys can lead to a transition from ordered to disordered growth due to the effect of disorder trapping. It is well known that the kinetics of crystal growth of intermetallic compounds is different from that of disordered solid solutions. In the present work containerless processing by electromagnetic levitation technique is used to measure the dendrite growth velocity as a function of undercooling during the solidification of undercooled Ni-Al (β- and γ′-phase) and Ti-Al (γ-phase) alloy melts of various compositions. The structure and microstructure investigations are performed in order to identify the primary solidified phases. Special attention is payed to investigation of chemically ordered intermetallic phases at the stoichiometric compositions 50:50 and 75:25. The experimental findings are interpreted within current theoretical models for disorder trapping and dendritic growth.