Kinetics of solidification of intermetallic compounds in the Ni-Al system
- Univ. of Cambridge (United Kingdom). Dept. of Materials Science and Metallurgy
- Deutsches Zentrum fuer Luft- und Raumfahrt, Cologne (Germany). Inst. fuer Raumsimulation
The kinetics of rapid solidification of chemically ordered intermetallics can be remarkably different from that of disordered solid solutions, resulting in substantial interfacial undercoolings or invertible partitioning. The present paper provides an analysis of the solidification kinetics of the L1{sub 2} and B2 phases in the Ni-rich part of the Ni-Al alloy system. Based on disorder-trapping and dendrite-growth models, the growth velocity, the compositions at the solid/liquid interface and the long-range order parameter have been calculated as a function of alloy composition and undercooling. Additionally, experimental studies on the competitive phase selection and growth behavior of these intermetallic phases and the disordered c.c.p. solid solution have been performed. In excellent agreement with the modeling, the direct kinetic measurements and microstructural studies on electromagnetically levitated Ni{sub 3}Al droplets show three phase-selection transitions (L1{sub 2} + B2 {yields} B2 {yields} disordered c.c.p. {yields} B2) at different levels of undercooling.
- OSTI ID:
- 616194
- Journal Information:
- Acta Materialia, Vol. 46, Issue 2; Other Information: PBD: 5 Jan 1998
- Country of Publication:
- United States
- Language:
- English
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