Investigation of the free volume change of Fe 41Co 7Cr 15Mo 14C 15B 6Y 2 bulk metallic glass using the cyclic thermal dilatation test

Xierong Zeng, Qiang Hu, Mingwang Fu, Shenghui Xie

Research output: Journal article publicationJournal articleAcademic researchpeer-review

4 Citations (Scopus)

Abstract

In heating process, the free volume of bulk metallic glass (BMG) changes with temperature. This change, however, is too small to be directly investigated by thermal dilatation (DIL) test. In cyclic heating, the free volume change results in a difference between the thermal expansion during heating and reheating processes, i.e., Δ(δV(T)/V 0), which can be obtained by the cyclic DIL test. In this paper, the sample diameter and pre-annealing effect on the free volume change of Fe 41Co 7Cr 15Mo 14C 15B 6Y 2 BMG are investigated by the Δ(δV(T)/V 0) and ΔδV/ V0̄, where ΔδV/ V0̄ is the average value of Δ(δV(T)/V 0) in the low temperature range and represents the total free volume released in the cyclic DIL test. The as-cast samples with a smaller diameter have a larger ΔδV/ V0̄. After pre-annealing below the glass transition temperature for 2 hours, a peak that is attributed to the free volume generation in glass transition process occurs in the Δ(δV(T,t a)/V 0) curve and becomes sharper as the pre-annealing time t a is prolonged. ΔδV( ta)/ V0̄ is fitted by a stretched exponential relaxation function with a characteristic relaxation time τ of 14194 ± 2808 s and a Kohlrausch exponent β kww of 0.34 ± 0.04. The β kww of Fe 41Co 7Cr 15Mo 14C 15B 6Y 2 BMG is markedly lower than that of Pd- and Zr-based BMGs, and deserves a further investigation.
Original languageEnglish
Pages (from-to)2682-2686
Number of pages5
JournalJournal of Non-Crystalline Solids
Volume358
Issue number18-19
DOIs
Publication statusPublished - 15 Sep 2012

Keywords

  • Bulk metallic glass
  • Free volume
  • Glass transition
  • Structural relaxation
  • Thermal dilatation

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Ceramics and Composites
  • Electronic, Optical and Magnetic Materials
  • Materials Chemistry

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