Homogeneous deformation of metallic glass at room temperature reveals large dilatation

Ke, Haibo; Wen, Ping; Peng, Hailong; Wang, W.H.; Greer, A.L.

doi:10.1016/j.scriptamat.2011.01.047

Cited by 100 publications

(54 citation statements)

References 29 publications

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“…Uniaxial compression of a BMG close to Yield Strength induced creep of the samples, accompanied by an increase in the stored heat of relaxation [134]. The sample exhibited an increase in compressive plasticity on the subsequent test [135].…”

Section: Effect Of Cyclic and Long-term Creep Deformation In The Elasmentioning

confidence: 96%

Mechanical Properties and Deformation Behavior of Bulk Metallic Glasses

Louzguine-Luzgin

Louzguina-Luzgina

Churyumov

2012

Metals

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Metallic glasses demonstrate unique properties, including large elastic limit and high strength, which make them attractive for practical applications. Unlike crystalline alloys, metallic glasses, in general, do not exhibit a strain hardening effect, while plastic deformation at room temperature is localized in narrow shear bands. Room-temperature mechanical properties and deformation behavior of bulk metallic glassy samples and the crystal-glassy composites are reviewed in the present paper.

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Section: Effect Of Cyclic and Long-term Creep Deformation In The Elasmentioning

confidence: 96%

Mechanical Properties and Deformation Behavior of Bulk Metallic Glasses

Louzguine-Luzgin

Louzguina-Luzgina

Churyumov

2012

Metals

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“…For elastostatic loading, this was studied by Ke et al [25]. A Zr-based BMG was subjected to uniaxial compression at 80% of σ y for 50 h. After that treatment, the viscoplastic strain ε v was −2.3 × 10 −5 (misprinted as −2.3 × 10 −4 in the original paper) and the fractional density change was −2.6 × 10 .…”

Section: Mechanism Of Disorderingmentioning

confidence: 99%

Stored energy in metallic glasses due to strains within the elastic limit

Greer

Sun

2016

Philosophical Magazine

108

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Room temperature loading of metallic glasses, at stresses below the macroscopic yield stress, raises their enthalpy and causes creep. Thermal cycling of metallic glasses between room temperature and 77 K also raises their enthalpy. In both cases, the enthalpy increases are comparable to those induced by heavy plastic deformation, but, as we show, the origins must be quite different. For plastic deformation, the enthalpy increase is a fraction (<10%) of the work done (WD) (and, in this sense, the behaviour is similar to that of conventional polycrystalline metals and alloys). In contrast, the room temperature creep and the thermal cycling involve small strains well within the elastic limit; in these cases, the enthalpy increase in the glass exceeds the WD, by as much as three orders of magnitude. We argue that the increased enthalpy can arise only from an endothermic disordering process drawing heat from the surroundings. We examine the mechanisms of this process. The increased enthalpy ('stored energy') is a measure of rejuvenation and appears as an exothermic heat of relaxation on heating the glass. The profile of this heat release (the 'relaxation spectrum') is analysed for several metallic glasses subjected to various treatments. Thus, the effects of the small-strain processing (creep and thermal cycling) can be better understood, and we can explore the potential for improving properties, in particular the plasticity, of metallic glasses. Metallic glasses can exhibit a wide range of enthalpy at a given temperature, and small-strain processing may assist in accessing this for practical purposes.

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“…Apart from the stress-induced instantaneous flow of yield, recent experiments and numerical simulations also demonstrated that a glass subject to stress, which is much smaller than its normal yield strength, can also undergo an extreme slow flowing, which is hard to be detected within a short period of time due to the slowness [4][5][6][7] . On the other hand, the universal nano-scaled localized b-relaxation in metallic glassy state has been observed before the large-scale a-relaxation, which has been demonstrated to be related to the nano-scaled microscopic hidden flowing phenomenon [8][9][10][11][12] .…”

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confidence: 99%

Evolution of hidden localized flow during glass-to-liquid transition in metallic glass

et al. 2014

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For glasses, the structural origin of their flow phenomena, such as elastic and plastic deformations especially the microscopic hidden flow before yield and glass-to-liquid transition (GLT), is unclear yet due to the lack of structural information. Here we investigate the evolution of the microscopic localized flow during GLT in a prototypical metallic glass combining with dynamical mechanical relaxations, temperature-dependent tensile experiments and stress relaxation spectra. We show that the unstable and high mobility nano-scale liquid-like regions acting as flow units persist in the glass and can be activated by either temperature or external stress. The activation of such flow units is initially reversible and correlated with b-relaxation. As the proportion of the flow units reaches a critical percolation value, a mechanical brittle-to-ductile transition or macroscopic GLT happens. A comprehensive picture on the hidden flow as well as its correlation with deformation maps and relaxation spectrum is proposed.

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Homogeneous deformation of metallic glass at room temperature reveals large dilatation

Cited by 100 publications

References 29 publications

Mechanical Properties and Deformation Behavior of Bulk Metallic Glasses

Mechanical Properties and Deformation Behavior of Bulk Metallic Glasses

Stored energy in metallic glasses due to strains within the elastic limit

Evolution of hidden localized flow during glass-to-liquid transition in metallic glass

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