Effect of pre-existing shear bands on mechanical properties and serration behaviors in bulk metallic glasses

The deformation and mechanical properties of Zr-based bulk metallic glasses (BMGs) under a nanoindenter and the effect of cooling rate, the effect of cooling rate, tungsten fiber addition and annealing on them have been studied by means of a nanoindentation instrument and a scanning electron microscope (SEM). The results indicate that the deformation of Zr-based BMGs under a nanoindenter is characterized by multiple shear bands and viscous flow which confirms the existence of a amount of plastic deformation. For pure quenched Zr-based BMGs, the larger the size of samples or the nearer the location away from the surface of a same sample, the smaller the values of microhardness (Hv) and elastic modulus (E); Annealing and tungsten fiber addition enhance the values of Hv and E; meanwhile, they also significantly change morphology around a nanoindenter and the amount of plastic deformation. The mechanism of plastic deformation is preliminarily analyzed.

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Formation and Mechanical Properties of Pd-Si Binary Bulk Metallic Glasses

Advances in Materials Science and Engineering ◽

10.1155/2014/647197 ◽

2014 ◽

Vol 2014 ◽

pp. 1-5

Author(s):

Na Chen ◽

Hongxia Zhang ◽

Ke-Fu Yao

Keyword(s):

Mechanical Properties ◽

Metallic Glasses ◽

Shear Bands ◽

Bulk Metallic Glasses ◽

High Strength ◽

Side Surface ◽

Alloy System ◽

Structural Inhomogeneity ◽

Micrometer Scale ◽

Scale Shear

Glassy spherical samples in the diameters up to 10 mm were produced in a binary Pd-Si alloy system. These Pd-Si bulk metallic glasses (BMGs) combine high strength of about 1600 MPa and superplasticity of over 70% together. In addition to abundant micrometer-scale shear bands, 10–20 nanometer-sized shear bands were also observed on the side surface of the deformed sample. The excellent ductility shown by the Pd-Si BMGs is suggested to arise from the nanoscale structural inhomogeneity.

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Mechanical properties of bulk metallic glasses and composites

Journal of Materials Research ◽

10.1557/jmr.2007.0050 ◽

2007 ◽

Vol 22 (2) ◽

pp. 285-301 ◽

Cited By ~ 308

Author(s):

J. Eckert ◽

J. Das ◽

S. Pauly ◽

C. Duhamel

Keyword(s):

Mechanical Properties ◽

Metallic Glasses ◽

Shear Bands ◽

Bulk Metallic Glasses ◽

Second Phase ◽

Matrix Composites ◽

Future Directions ◽

Glassy Alloys ◽

Spatially Inhomogeneous ◽

Glass Matrix Composites

The development of bulk metallic glasses and composites for improving the mechanical properties has occurred with the discovery of many ductile metallic glasses and glass matrix composites with second phase dispersions with different length scales. This article reviews the processing, microstructure development, and resulting mechanical properties of Zr-, Ti-, Cu-, Mg-, Fe-, and Ni-based glassy alloys and also considers the superiority of composite materials containing different phases for enhancing the strength, ductility, and toughness, even leading to a “work-hardening-like” behavior. The morphology, shape, and length scale of the second phase dispersions are crucial for the delocalization of shear bands. The article concludes with some comments regarding future directions of the investigations of spatially inhomogeneous metallic glasses.

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