Correlation between enthalpy change and free volume reduction during structural relaxation of Zr55Cu30Al10Ni5 metallic glass

Slipenyuk, A.; Eckert, J.

doi:10.1016/j.scriptamat.2003.09.038

Cited by 507 publications

(231 citation statements)

References 13 publications

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“…It is well known that prior to T g , the exothermic event (i.e. the heat release during relaxation) is indicative of the existence of free volume in BMGs [20].…”

Section: Resultsmentioning

confidence: 99%

“…The microstructure of these samples was identified through high resolution transmission electron microscope (HRTEM; JEOL Ltd. JEM-2100F). The free volume changes were indirectly measured using the differential scanning calorimetry (DSC) method [19,20]. The DSC tests were conducted using a Setaram DSC 2000 with a 800°C rod at a heating rate of 0.33 K s À1 in a flow of argon, and a second run under identical conditions was used to determine the base line after each measurement.…”

Section: Experimental Methodsmentioning

confidence: 99%

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Shear transformation zone volume determining ductile–brittle transition of bulk metallic glasses

et al. 2011

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Three-point bending experiments were performed on as-cast and annealed samples of Zr 52.5 Cu 17.9 Ni 14.6 Al 10 Ti 5 (Vit105) bulk metallic glasses over a wide range of temperatures varying from room temperature (293 K) to liquid nitrogen temperature (77 K). The results demonstrated that the free volume decrease due to annealing and/or cryogenic temperature can reduce the propensity for the formation of multiple shear bands and hence deteriorate plastic deformation ability. We clearly observed a sharp ductile-to-brittle transition (DBT), across which microscopic fracture feature transfers from micro-scale vein patterns to nano-scale periodic corrugations. Macroscopically, the corresponding fracture mode changes from ductile shear fracture to brittle tensile fracture. The shear transformation zone volume, taking into account free volume, temperature and strain rate, is proposed to quantitatively characterize the DBT behavior in fracture of metallic glasses.

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“…It is well known that prior to T g , the exothermic event (i.e. the heat release during relaxation) is indicative of the existence of free volume in BMGs [20].…”

Section: Resultsmentioning

confidence: 99%

Section: Experimental Methodsmentioning

confidence: 99%

Shear transformation zone volume determining ductile–brittle transition of bulk metallic glasses

et al. 2011

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“…The latter involves a long-range rearrangement of atoms associated with the redistribution and reduction of the excess free volume. 2 The decrease of the free volume upon annealing results in higher viscosity, 5 density, 6 and tensile strength, 7 lower plasticity, 7,8 and better soft magnetic properties. 9 Hence, characterization of the excess free volume is important for understanding the relationship between the atomic structure and properties of MGs.…”

Section: Introductionmentioning

confidence: 99%

“…9 Hence, characterization of the excess free volume is important for understanding the relationship between the atomic structure and properties of MGs. The evolution of the excess free volume upon isothermal or isochronal annealing has been widely investigated by density measurements, 6 positron annihilation spectroscopy (PAS), 10 calorimetric measurements, 4 dilatometry, 11 and X-ray diffraction (XRD) 2 . In-situ high-energy synchrotron XRD is a particularly useful method to study the changes in the atomic structure and thermal expansion of the MGs at different temperatures.…”

Section: Introductionmentioning

confidence: 99%

Thermal and soft magnetic properties of Co40Fe22Ta8B30 glassy particles: In-situ X-ray diffraction and magnetometry studies

Taghvaei

Stoica

Kaban

et al. 2014

Journal of Applied Physics

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Articles you may be interested inThe soft magnetic properties of ring-shaped (Co0.6Fe0.3Ni0.1)68(B0.811Si0.189)27Nb5 bulk metallic glasses J. Appl. Phys. 113, 17A336 (2013) The structural evolution of Co 40 Fe 22 Ta 8 B 30 glassy particles has been studied by in-situ high-energy synchrotron X-ray diffraction (XRD) upon isochronal annealing. The changes in position, intensity, and full width at half maximum (FWHM) of the first and second diffuse maxima of the XRD patterns suggest the occurrence of irreversible structural relaxation upon the first heating up to a temperature close to the glass transition temperature T g . The variations in reduced pair correlation functions upon annealing are discussed in the frame of the topological fluctuation theory for structural relaxation. Isochronal annealing of the Co 40 Fe 22 Ta 8 B 30 glassy particles improves their soft magnetic properties through decreasing the coercivity and increasing the magnetic susceptibility, saturation magnetization, and Curie temperature. V C 2014 AIP Publishing LLC.

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“…Obviously, the mechanical properties of metallic glasses are closely related to the free-volume content. Four methods can be used to change free-volume content: cooling the melt at different rates during solidification [11], annealing the metallic glass below the glass-transition temperature [12], reheating the metallic glass to above the glasstransition temperature and then cooling down quickly [13], and plastic deformation [14][15][16][17]. The principle behind these methods is that metallic glasses are thermodynamically metastable.…”

mentioning

confidence: 99%

Rolling-induced microstructure change in Zr65Al7.5Ni10Cu12.5Ag5 bulk metallic glass

Zhou

Kong

et al. 2011

Chin. Sci. Bull.

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The microstructures and free-volume evolutions of as-cast and pre-annealed Zr 65 Al 7.5 Ni 10 Cu 12.5 Ag 5 bulk metallic glasses during rolling deformation have been investigated. No phase transformation is detected in the as-cast/rolled specimen. However, the structural stability of the glass against plastic deformation is worse after pre-annealing, indicated by nanocrystallization in preannealed/rolled specimens with large deformation degrees. Moreover, with increasing deformation degree, the free-volume content in a pre-annealed/rolled specimen increases at a lower average rate than that in an as-cast/rolled specimen. Bulk metallic glasses (BMGs) have attracted much attention because of their properties such as high fatigue strength, high hardness, good castability, and excellent wear and corrosion resistances [1][2][3][4][5][6][7][8]. However, during compressive or tensile tests at temperatures far below the glass-transition temperature, failure of BMGs usually occurs along a single shear band without much macroscopic plasticity. Their low global plasticity and ductility limit their applications as engineering materials [9], and much attention has been focused on their deformation and fracture mechanisms. Spaepen showed that plastic deformation in a metallic glass is realized by a series of atomic diffusional jumps associated with free volume [10]. The introduction of free volume into shear bands leads to a local lowering of the viscosity, and, as a result, an abrupt break takes places along the shear band. Obviously, the mechanical properties of metallic glasses are closely related to the free-volume content. Four methods can be used to change free-volume content: cooling the melt at different rates during solidification [11], annealing the metallic glass below the glass-transition temperature [12], reheating the metallic glass to above the glasstransition temperature and then cooling down quickly [13], and plastic deformation [14][15][16][17]. The principle behind these methods is that metallic glasses are thermodynamically metastable. Their structure can be changed from one state to another state by heating or mechanical deformation. Many studies have addressed the effects of plastic deformation on the free-volume content of metallic glasses [18][19][20], but very little attention has been paid to the dependence of freevolume evolution during deformation on the initial state of the glass. In this study, rolling deformation was performed on as-cast and pre-annealed Zr 65 Al 7.5 Ni 10 Cu 12.5 Ag 5 BMGs, and their free-volume content evolutions were investigated. Experimental procedureAlloy ingots of nominal composition Zr 65 Al 7.5 Ni 10 Cu 12.5 Ag 5 (atomic per cent) were prepared by arc melting a mixture of pure Zr (99.9%), Al (99.99%), Ni (99.99%), Cu (99.99%), and Ag (99.99%) under a Ti-gettered argon atmosphere. The ingots were inverted and remelted six times to ensure

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Correlation between enthalpy change and free volume reduction during structural relaxation of Zr55Cu30Al10Ni5 metallic glass

Cited by 507 publications

References 13 publications

Shear transformation zone volume determining ductile–brittle transition of bulk metallic glasses

Shear transformation zone volume determining ductile–brittle transition of bulk metallic glasses

Thermal and soft magnetic properties of Co40Fe22Ta8B30 glassy particles: In-situ X-ray diffraction and magnetometry studies

Rolling-induced microstructure change in Zr65Al7.5Ni10Cu12.5Ag5 bulk metallic glass

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