Structural relaxation kinetics defines embrittlement in metallic glasses
نویسندگان
چکیده
Article history: Received 5 December 2017 Received in revised form 22 January 2018 Accepted 23 January 2018 Available online xxxx Structural relaxation during isothermal annealing, quantified by enthalpy recovery of Zr44Ti11Cu10Ni10Be25 towards its metastable equilibrium and correlation to embrittlement, quantified through fracture toughness, KQ, is studied. Enthalpy relaxation over time obeys the Kohlrausch-William-Watts (KWW) stretch exponent with β = 0.74 and τ = 11,000 s. Such β and τ are used to fit experimental KQ(t) with KWW, resulting in R = 0.79. This finding combined with a controlled characterization of the glasses'KQ versus temperature, fictive temperature, and their combination, revealed that embrittlement inmetallic glasses is predominantly controlled by structural rearrangements, whereas volume changes from thermal expansion have negligible influence. © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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