Structural features of plastic deformation in bulk metallic glasses

Abstract

Spatially resolved strain maps of a plastically deformed bulk metallic glass (BMG) have been created by using high-energy X-ray diffraction. The results reveal that plastic deformation creates a spatially heterogeneous atomic arrangement, consisting of strong compressive and tensile strain fields. In addition, significant shear strain is introduced in the samples. The analysis of the eigenvalues and eigenvectors of the strain tensor indicates that considerable structural anisotropy occurs in both the magnitude and direction of the strain. These features are in contrast to the behavior observed in elastically deformed BMGs and represent a distinctive structural sign of plastic deformation in metallic glasses.

Ductile bulk metallic glass by controlling structural heterogeneities

“…Imprinting, however, induces significant residual strain (and stress) in the material 32 , which may in turn interact with the stress concentration experienced by the material at the matrix-fiber interfaces (Fig. 8).…”

Structural aspects of elasto-plastic deformation of a Zr-based bulk metallic glass under uniaxial compression

“…This can be attributed to some irreversible structural 425 changes that have occurred in this direction during deformation, 426 irreversibly altering the structure. [49,50]. 433 In the different MRO shells, the atomic strains are almost similar 434 in the elastic regime.…”

“…Alternatively, the formation 48 and propagation of localized shear bands nucleated from shear 49 transformation zones (STZs) is the most accepted mechanism of 50 room temperature plastic deformation in BMGs [1]. The proposed [3,4] ing (for details on sample preparation see [19]).…”

Bulk Metallic Glasses as Structural Materials: A Review

“…In addition to cold rolling, other mechanical treatments have also been utilized to improve the mechanical properties of BMGs. A more novel mechanical treatment involves mechanically imprinting BMG plates between imprinting tools embossed with a regular array of linear teeth spaced a few hundreds of micrometers apart (Figure ) . A high density of shear bands form immediately under the imprinting teeth while also a smaller number of shear bands are driven through the thickness of the plate.…”

“…A high density of shear bands form immediately under the imprinting teeth while also a smaller number of shear bands are driven through the thickness of the plate. This induces i) a heterogeneous microstructure throughout the BMG of locally hard and soft regions, ii) a heterogeneous residual stress field of locally tensile and compressive residual stresses, and iii) structural anisotropy over distances of <5 Å . Microhardness mapping indicated that soft regions were created under the impressions, while hardening occurred between them (Figure a and b).…”