Transition from hypereutectic to hypoeutectic for rapid solidification in an undercooled Co-B alloy

Yixuan He, Jinshan Li, Jun Wang, Eric Beaugnon

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Phase selection, a common and important phenomenon in rapid solidification, determines the solidification sequence and the mechanical/physical properties. In this work, a Co-20 at%B hypereutectic alloy was undercooled by the melt fluxing technique and the microstructure was characterized by the back-scattering diffraction technique. A transition from hypereutectic to hypoeutectic was found at a critical undercooling of ΔT = 119 K. When ΔT < 119 K, a primary directional dendritic β-Co3B phase surrounded by the regular α-Co + β-Co3B lamellar eutectics was found. When ΔT > 119 K, the above hypereutectic microstructure changes into hypoeutectic structure with the α-Co phase as the primary phase. According to dendrite growth model, the transition from hypereutectic to hypoeutectic can be ascribed to the higher growth velocity of the α-Co phase than the β-Co3B phase, i.e., the growth-controlled mechanism. The current work shows also that there is a coupled zone skewed to the β-Co3B phase in the Co-B alloys system.

Original languageEnglish
Pages (from-to)98-105
Number of pages8
JournalJournal of Crystal Growth
Volume499
DOIs
StatePublished - 1 Oct 2018

Keywords

  • A1. Eutectics
  • A1. Solidification
  • A2. Growth from melt
  • B1. Alloys

Fingerprint

Dive into the research topics of 'Transition from hypereutectic to hypoeutectic for rapid solidification in an undercooled Co-B alloy'. Together they form a unique fingerprint.

Cite this