Improved plasticity of bulk metallic glasses upon cold rolling

Lee, M.H.; Lee, K.S.; Das, J.; Thomas, Jürgen; Kühn, U.; Eckert, J.

doi:10.1016/j.scriptamat.2010.01.024

Cited by 129 publications

(45 citation statements)

References 39 publications

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“…Similar toughening effects in BMGs were also reported in [21,25]. For instance, the cold rolling technique was successfully applied to introduce profuse shear bands in glassy alloys, and the as-rolled samples indeed displayed enhanced ductility under bending deformation [20,25]. The effective multiplication of shear bands during post-deformation was observed in samples with ~29% pre-deformation amount in Vit4 BMG [21].…”

Section: Resultssupporting

confidence: 66%

“…Large plasticity has also been obtained by shot-peening [16], electrodeposition [17,18] and use of a metal sleeve [19]. Very recently it has been found that introducing a uniform distribution of shear bands by rolling and pre-deformation can improve the plasticity of BMGs [20,21]. To understand the effects of pre-introduced shear bands on the subsequent deformation behavior of BMGs, the compressive behavior of pre-deformed Zr 41 Ti 14 -Cu 12.5 Ni 10 Be 22.5 (Vit1) BMGs has been studied in the present work.…”

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confidence: 99%

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Work toughening effect in Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass

2011

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Work hardening is a well-known phenomenon occurring in crystalline metals during deformation, which has been widely used to increase the strength of metals although their ductility is usually reduced simultaneously. Here we report that the plastic strain of Zr 41 Ti 14 Cu 12.5 Ni 10 Be 22.5 (at.%) bulk metallic glasses has been increased from 0.3% for the as-cast sample to 2.5%-8.0% for samples that have experienced pre-deformation under constrained conditions. The pre-deformed glassy alloys possess more free volume and abundant introduced shear bands, which are believed to promote the activation of shear bands in post-deformation and result in an increase in plasticity. The orientation of the pre-introduced shear bands relative to the loading direction will affect the deformation behavior of pre-deformed samples. The present results show that pre-deformation of this glassy alloy will result in work toughening. This work toughening effect can be removed by isothermal annealing at a sub-T g (glass transition) temperature, which causes annihilation of free volume and healing of shear bands. It is well known that most bulk metallic glasses (BMGs) possess super-high strength but very low global plasticity. The accepted reason for the limited plasticity of BMGs is that BMGs possess a tendency to form highly-localized shear bands which result in early fracture of the materials. It is obvious that deformation behavior of BMGs is quite different from crystalline metals, in which plastic deformation corresponds to the generation and motion of large numbers of dislocations. As the dislocation density increases with the plastic deformation, the interactions among dislocations are also increased, resulting in an increase in the resistance to dislocation movement. Then, further deformation requires an increase in the applied stress. This is the so-called "strain hardening" or "work hardening". However, since there are no dislocations in glassy alloys, absolutely no strain hardening resulting from interactions among dislocations can be observed in BMGs. So it is very difficult for glassy alloys to deform uniformly. Instead, highly localized shear bands [1] form easily during the deformation process, resulting in limited global plasticity of BMG. So to enhance the plasticity of BMGs, it is necessary to promote the activation of multiple shear bands [2-10] and hinder the localization and rapid propagation of shear bands [11][12][13][14][15][16][17][18][19]. Indeed much important progress has been made in enhancing the ductility of BMGs by various ways [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], such as by introducing second phase particles on the nanoscale/microscale [2][3][4][5] or solid solution particles [6] which restrict the severe localization and rapid propagation of shear bands, the as-prepared BMG composites could exhibit a global plasticity of about 7% [7]. Because the partially relieved local heating and hindrance of the propagation of shear bands, both the strength and the ductility of a Zr-bas...

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Section: Resultssupporting

confidence: 66%

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confidence: 99%

Work toughening effect in Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass

2011

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“…Also, the compressive and tensile mechanical properties of Zr-based bulk metallic glasses were reported to be modified by pre-deformation via cold rolling [13,14]. On the other hand, some investigations reported an absence of (or inefficient) influence of shear bands on the properties of metallic glasses [14,15]. Thus, the properties of a deformed metallic glass are or are not affected by the shear bands.…”

Section: Introductionmentioning

confidence: 99%

The impact of elastic and plastic strain on relaxation and crystallization of Pd–Ni–P-based bulk metallic glasses

et al. 2015

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“…1,2 Recently, great efforts have been made to enhance the plastic deformation capability of BMGs. Apart from the composite strategy, several attempts have been made to improve the plasticity of monolithic BMGs, including prior cold rolling, 3,4 and shot peening. 5 The improved plasticity is attributed to the induced residual stress and the implanted shear bands.…”

Section: Introductionmentioning

confidence: 99%

Deformation feature and properties of Zr based bulk metallic glass treated by laser shock peening

Yan

Wei

2014

Materials Research Innovations

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Laser shock peening is promising surface treatment technique to improve the mechanical properties of metals material through introducing a deep compressive residual stresses region. In this work, LSP was employed to treat Zr based bulk metallic glasses (BMGs). In contrast to the work softening in BMGs, laser shock peened BMG shows significant hardening in the plastic deformed region. Furthermore, the plastic deformation region exhibits unique deformation features, which is dependent on the thickness of the samples. The deformation morphology under the impacted region was also studied. The mechanism for the hardening and formation of unique deformation features is discussed.

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Improved plasticity of bulk metallic glasses upon cold rolling

Cited by 129 publications

References 39 publications

Work toughening effect in Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass

Work toughening effect in Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass

The impact of elastic and plastic strain on relaxation and crystallization of Pd–Ni–P-based bulk metallic glasses

Deformation feature and properties of Zr based bulk metallic glass treated by laser shock peening

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