Details

Autor(en) / Beteiligte

• Cao, C.D
• Xie, W.J
• Wei, B

Titel

Microstructural characterization of cobalt–antimony eutectic alloy droplets solidified in drop tube

Ist Teil von

• Materials science & engineering. A, Structural materials : properties, microstructure and processing, 2000-05, Vol.283 (1), p.86-93

Ort / Verlag

Amsterdam: Elsevier B.V

Erscheinungsjahr

2000

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Co–Sb alloy droplets have been solidified during free fall in a 3 m drop tube. The cooling rate and undercooling are estimated versus droplet diameter, both of which play a dominant part in dendritic and eutectic growth. The eutectic coupled zone has been calculated on the basis of TMK and LKT/BCT theories, which covers a composition range from 22.7% to 49%Sb. A ‘lamellar-anomalous’ eutectic transition occurs to Co-41.4%Sb droplets with the increase of undercooling. For Co-20%Sb hypoeutectic alloy, primary α-Co phase experiences a ‘dendritic to equiaxed’ structural morphology transition and an abrupt grain refinement at a critical undercooling of about 88 K under drop tube conditions. The remaining interdendritic liquid does not solidify in a mode of eutectic growth but forms into a divorced structure under drop tube conditions. The primary β-CoSb intermetallic compound of Co-45%Sb hypereutectic alloy grows in a dendritic way inside droplet and forms as a spherical shell on droplet surface. Most Co-45%Sb droplets undercooled by 80∼130 K exhibit complete eutectic microstructures. Significant solute trapping takes place in primary α-Co and β-CoSb dendrites.