Structural relaxation kinetics defines embrittlement in metallic glasses

SCRIPTA MATERIALIA

卷:149

Article

Ketkaew, Jittisa¹  Fan, Meng¹  Shattuck, Mark D.^1,2,3  O'Hern, Corey S.^1,4,5  Schroers, Jan¹ 

[1] Yale Univ, Dept Mech Engn & Mat Sci, New Haven, CT 06511 USA

[2] CUNY City Coll, Dept Phys, New York, NY 10031 USA

[3] CUNY City Coll, Benjamin Levich Inst, New York, NY 10031 USA

[4] Yale Univ, Dept Phys, New Haven, CT 06511 USA

[5] Yale Univ, Dept Appl Phys, New Haven, CT 06520 USA

关键词: Bulk metallic glass;    Fracture toughness;    Aging;    Annealing;    Relaxation kinetics;   

DOI  :  10.1016/j.scriptamat.2018.01.024

来源: Elsevier

【 摘 要 】

Structural relaxation during isothermal annealing, quantified by enthalpy recovery of Zr44Ti11Cu10Ni10Be25 towards its metastable equilibrium and correlation to embrittlement, quantified through fracture toughness, K-Q, is studied. Enthalpy relaxation over time obeys the Kohlrausch-William-Watts (KWW) stretch exponent with beta = 0.74 and tau = 11,000 s. Such beta and tau are used to fit experimental K-Q(t) with KWW, resulting in R-2 = 0.79. This finding combined with a controlled characterization of the glasses' K-Q versus temperature, fictive temperature, and their combination, revealed that embrittlement in metallic glasses is predominantly controlled by structural rearrangements, whereas volume changes from thermal expansion have negligible influence. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

【 授权许可】

Free