Solidification kinetics and phase formation of undercooled eutectic Ni-Nb melts
- Inst. fuer Festkoerper- und Werkstofforschung Dresden (Germany)
The non-equilibrium solidification behavior of undercooled eutectic Ni{sub 84}Nb{sub 16} and Ni{sub 59.5}Nb{sub 40.5} melts has been analyzed by in situ observation of recalescence events during electromagnetic levitation of undercooled melts. Levitated drops of controlled undercooling were quenched onto chill substrates and subjected to phase and microstructure analysis. For Ni{sub 84}Nb{sub 16} a maximum melt undercooling of 276 K has been achieved. A transition from coupled eutectic to primary supersaturated {alpha}-Ni dendrite growth has revealed beyond a critical undercooling of 30 K. Beyond 110 K the primary Ni{sub 3}Nb phase occurred for substrate quenching. The undercooling of Ni{sub 59.5}Nb{sub 40.5} melt was limited to 135 K. Bulk amorphous samples up to 2 mm thick have been prepared by quenching of undercooled Ni{sub 59.5}Nb{sub 40.5} melts. On slow cooling the metastable phases decompose into an anomalous eutectic microstructure.
- OSTI ID:
- 684396
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Journal Issue: 10 Vol. 47; ISSN 1359-6454; ISSN ACMAFD
- Country of Publication:
- United States
- Language:
- English
Similar Records
Undercooled and rapidly quenched Ni-Mo alloys
Microtexture and macrotexture formation in the containerless solidification of undercooled Ni-18.7 at.% Sn eutectic melts