Phase Selection in Solidification of Undercooled Co–B Alloys. Issue 4 (April 2017)

• Record Type: Journal Article
• Authors: Wei, X.X.; Xu, W.; Kang, J.L.; Ferry, M.; Li, J.F.
• Is Part Of: Journal of materials science & technology. Volume 33:Issue 4(2017:Apr.)
• Page Start: 352
• Page End: 358
• Publication Date: 2017-04
• Subjects: Undercooling -- Rapid solidification -- Metastable phase diagram -- Structure evolution; Metals -- Periodicals; Materials science -- Periodicals; Materials science; Metals; Periodicals; 620.1105
• DOI: 10.1016/j.jmst.2016.09.012
• Languages: English
• ISSNs: 1005-0302

Abstract

Abstract : A series Co-(18.5–20.7) at.% B melts encompassing the eutectic composition (Co81.5 B18.5 ) were solidified at different degrees of undercooling. It is found that the metastable Co23 B6 phase solidifies as a substitute for the stable Co3 B phase in the alloy melts undercooled above a critical undercooling value of ~60 K. The Co23 B6 and α-Co phases make up a metastable eutectic. The corresponding eutectic composition and temperature are Co80.4 B19.6 and 1343 K, respectively. On exposure of the metastable Co23 B6 phase at a given temperature above 1208 K, it does not decompose even after several hours. But it transforms by a eutectoid reaction to α-Co + Co3 B at lower temperature.