Peer ReviewedPostprint (published version

Giordano, Valentina

Luettich, Martin

Luo, Y.

Pineda Soler, Eloi

Ruta, Beatrice

Samwer, Konrad

English

UPCommons

Tuning the memory dependence of vapour deposited metallic glasses

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I8 - Tue 09:00-09:30 Heat Treatment/Devitrication Kleiner Saal / Small HallStructural rejuvenation with the change of local structure and mechanical properties in recovery annealed Zr-based metallic glasses   Junji Saida1, Rui Yamada1, Wei Guo1, Masato Wakeda2 and Shigenobu Ogata2    1 Frontier Research Institute for Interdisciplinary Sciences (FRIS), Tohoku University, Sendai, Japan 2 Graduate School of Engineering Science, Osaka University, Osaka, Japan  Recently, structural rejuvenation, i.e., recovery of the less relaxed state, in metallic glasses has been attracted attention from the viewpoints of improving mechanical properties as well as understanding a relaxation phenomenon originating from the intrinsic random atomic configuration. Relaxation state is generally regarded as one of the important parameters on various properties of metallic glass. Especially, since the good mechanical properties are usually lost by relaxation, we have to control it carefully for industrial use. The authors have investigated that the relaxation state is fixed by the cooling rate in the lower temperature region of the supercooled liquid state [1]. Based on the results, we have reported the recovery of less relaxed state (rejuvenation) of metallic glass through a simple thermal processing by annealing just above glass transition temperature followed by an appropriate cooling using the experimental [2] and simulation studies [3]. Here, it is found that the history of the relaxation is reset in the temperature around 1.1-1.2Tg, and the new relaxation state is introduced depending on the following (final) cooling rate by molecular dynamics (MD) simulation. Actually, the relaxation enthalpy can be got back (that is, the glassy alloy can be rejuvenated) for the almost fully relaxed glassy alloy by post annealing at 1.07Tg  followed by the appropriate cooling at approximately 4 K/s in the Zr55Al10Ni5Cu30 metallic glass. In this presentation, we intend to evaluate the condition for rejuvenation in metallic glass and discuss on the change of local structure and mechanical properties by rejuvenation. The present study proposes a novel method on controlling relaxation state and provides useful information on the application of metallic glasses.  References:  [1] J. Saida, A.D. Setyawan, H. Kato and A. Inoue, Met. Mater. Trans. A, 42, 1450 (2011). [2] J. Saida, R. Yamada and M. Wakeda, Appl. Phys. Lett., 103, 221910 (2013). [3] M. Wakeda, J. Saida, J. Li and S. Ogata, Sci. Rep., 5, 10545 (2015). C22 - Tue 09:30-09:50 Heat Treatment/Devitrication Kleiner Saal / Small HallTuning the memory dependence of vapour deposited metallic glassesM. Lu¨ttich1,2, B. Ruta1, Y. Luo2, K. Samwer2, V.M. Giordano3, E. Pineda41 ESRF-The European Synchrotron, 38043 Grenoble Cedex 9, France2 I. Institute of Physics, University of Go¨ttingen, Germany3 Institute of Light and Matter, Universite´ de Lyon 1-CNRS, France3 Polytechnic University of Catalonia Barcelona, Catalunya, SpainMetallic glasses (MGs) show outstanding mechanical, physical and chemical properties and so provide a whole class of materials atthe cutting-edge research in metallic and glassy systems [1]. By exposing them to thermal treatments, their properties get affectedin a subtle and complex way. We present here a study of memory effects due to different thermal treatments in the atomic motion ofrapidly quenched and vapour deposited CuZr MGs by means of x-ray photon correlation spectroscopy (XPCS). Vapour deposition issupposed to give rise to ultra-stable MGs, that is MGs with improved stability [2]. However information on their dynamics at the atomiclevel is still missing.While cycling through a temperature protocol and measuring the dynamics of density fluctuations at different isothermal temperaturesteps, we find that vapour deposited MGs show a vanishing history dependence with rising annealing temperatures Ta < Tg .T ′a; although the absolute value of the relaxation time τ behaves inversely proportional with Ta. Moreover the dynamics in vapourdeposited MGs is stationary while, in contrast, the fast quenched MG show the occurrence of aging during isotherm measurements.[1] W.-H. Wang, Prog. Mater. Sci. 57, 487–656 (2012).[2] H.-B. Yu, Y. Luo, K. Samwer, Adv. Mater. 25, 5904–5908 (2013).34

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Tuning the memory dependence of vapour deposited metallic glasses

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