Localized plastic deformation in a model metallic glass: a survey of free volume and local force distributions

Vickers and nano indentations were performed on a structurally relaxed Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG), and the evolution of the shear bands in the relaxed BMG was investigated and compared to that in the as-cast alloy. Results indicate that the plastic deformation in the BMG with structure relaxation is accommodated by the semicircular (primary) and radial (secondary) as well as tertiary shear bands. Quantitatively, the shear band density in the relaxed alloy was much lower than that in the as-cast alloy. The annihilation of free volume caused by the annealing was responsible for the embrittlement of the sample with structure relaxation.

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OS19-4-5 Influence of free volume change on plastic deformation behavior in Zr-Cu-Al ternary bulk metallic glass

The Abstracts of ATEM International Conference on Advanced Technology in Experimental Mechanics Asian Conference on Experimental Mechanics ◽

10.1299/jsmeatem.2011.10._os19-4-5- ◽

2011 ◽

Vol 2011.10 (0) ◽

pp. _OS19-4-5-

Author(s):

R. Ito ◽

T. Kimura ◽

Y. Takigawa ◽

T. Uesugi ◽

K. Amiya ◽

...

Keyword(s):

Plastic Deformation ◽

Metallic Glass ◽

Bulk Metallic Glass ◽

Free Volume ◽

Volume Change ◽

Deformation Behavior ◽

Plastic Deformation Behavior

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Free-volume dependent pressure sensitivity of Zr-based bulk metallic glass

Journal of Materials Research ◽

10.1557/jmr.2009.0304 ◽

2009 ◽

Vol 24 (8) ◽

pp. 2697-2704 ◽

Cited By ~ 16

Author(s):

Alban Dubach ◽

K. Eswar Prasad ◽

Rejin Raghavan ◽

Jorg F. Löffler ◽

Johann Michler ◽

...

Keyword(s):

Plastic Deformation ◽

Metallic Glass ◽

Bulk Metallic Glass ◽

Free Volume ◽

Structural State ◽

Shear Bands ◽

Compressive Yield Strength ◽

Pressure Sensitivity ◽

Constraint Factor ◽

Shear Transformation Zones

Instrumented indentation experiments on a Zr-based bulk metallic glass (BMG) in as-cast, shot-peened and structurally relaxed conditions were conducted to examine the dependence of plastic deformation on its structural state. Results show significant differences in hardness, H, with structural relaxation increasing it and shot peening markedly reducing it, and slightly changed morphology of shear bands around the indents. This effect is in contrast to uniaxial compressive yield strength, σy, which remains invariant with the change in the structural state of the alloys investigated. The plastic constraint factor, C = H/σy, of the relaxed BMG increases compared with that of the as-cast glass, indicating enhanced pressure sensitivity upon annealing. In contrast, C of the shot-peened layer was found to be similar to that observed in crystalline metals, indicating that severe plastic deformation could eliminate pressure sensitivity. Microscopic origins for this result, in terms of shear transformation zones and free volume, are discussed.

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Plastic Deformation and Mechanical Softening of Pd40Cu30Ni10P20 Bulk Metallic Glass During Nanoindentation

Journal of Materials Research ◽

10.1557/jmr.2005.0331 ◽

2005 ◽

Vol 20 (10) ◽

pp. 2719-2725 ◽

Cited By ~ 38

Author(s):

A. Concustell ◽

J. Sort ◽

G. Alcalá ◽

S. Mato ◽

A. Gebert ◽

...

Keyword(s):

Plastic Deformation ◽

Metallic Glass ◽

Bulk Metallic Glass ◽

Free Volume ◽

Loading Rate ◽

Shear Bands ◽

Control Mode ◽

Displacement Control ◽

Softening Effect ◽

Wide Range

Nanoindentation tests of Pd40Cu30Ni10P20 bulk metallic glass were performed over a wide range of indentation rates (from 0.04 up to 6.4 mN s−1) under the standard load control mode. New results using the feedback displacement control mode are also presented. The dependence of the pop-in formation on the loading rate is investigated. Variations in hardness and reduced elastic modulus as a function of the indentation rate are observed. A softening effect occurs when increasing the loading rate. This is explained by the differences in plastic deformation achieved at different indentation rates. The displacement control mode was used to avoid the shear localization of the free volume, leading to the almost complete absence of pop-ins along the loading curve. The obtained results suggest that plastic flow in bulk metallic glasses is governed by the rate of creation of free volume, which depends on the strain rate and its localization into shear bands.

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