Discontinuities of Plastic Deformation in Metallic Glasses Ing. Mária Huráková školiteľ: RNDr. Kornel Csach, CSc. Ústav experimentálnej fyziky Slovenská akadémia vied Oddelenie fyziky kovov Súťaž mladých vedeckých pracovníkov do 35 rokov, 10. december 2015

Publikácie za rok 2015 Huráková M., Csach K., Juríková A., Miškuf J., Rajňák M., Kvačkaj T.: Structural stability of amorphous alloy of modified Finemet type, In: Acta Physica Polonica A 127 (2015) pp (0.604-IF2014). ( Current Contents, WOS, SCOPUS). ISSN Typ: ADCA Miškuf J., Csach K., Juríková A., Huráková M., Tabachnikova E.D.: Fragmentation of Co-Fe-Ta-B soft magnetic amorphous alloy, In: Acta Physica Polonica A 127 (2015) pp (0.604-IF2014). ( Current Contents, WOS, SCOPUS) ISSN Typ: ADCA Longauerová M., Huráková M., Bekeč P., Longauer S., Fedorová M., Konrádyová J.: Local notch toughness of slab surface zone in ULC/IF and HSLA steels, In: Key Engineering Materials 662 (2015) pp Typ: ADM Csach K., Miškuf J., Juríková A., Huráková M., Ocelík V., De Hosson J.Th.M.: Nanoindentation in metallic glasses with different plasticity, In: Key Engineering Materials 662 (2015) pp Typ: ADM Miškuf J., Csach K., Juríková A., Huráková M., Miškuf M., Tabachnikova E., Psaruk I., Laktionova M., Podolskiy A.: Generation of nanoscale stripes at failure of amorphous metals, In: Key Engineering Materials 662 (2015) pp Typ: ADM Huráková M., Csach K., Juríková A., Miškuf J., Demčák Š., Ocelík V., De Hosson J.Th.M.: Nanoindentation study of the influence of the loading rate on the deformation of metallic glasses, In: Key Engineering Materials 662 (2015) pp Typ: ADM Longauerová M., Fedorová M., Bekeč P., Duška J., Huráková M., Longauer S., Konrádyová J.: Effect of sample thickness on slab surface zone toughness in IF and microalloyed steels, Key Engineering Materials Vol. 647 (2015) pp Typ: ADM Bálintová M., Demčák Š., Holub M., Huráková M.: Partial sulphate precipitation with iron oxidation in acid mine waters (Slovakia), SGEM 2015 (2015) pp Typ: ADM Huráková M., Csach K., Miškuf J., Juríková A., Demčák Š., Ocelík V., De Hosson J.Th.M.: Shear failure of amorphous alloy at nanoindentation, Powder Metallurgy Progress Vol. 15 (2015) pp Typ: AFD

Publikácie Huráková M., Csach K., Juríková A., Miškuf J., Demčák Š., Ocelík V., De Hosson J.Th.M.: Discontinuities of Plastic Deformation in Metallic Glasses with Different Glass Forming Ability (Physics Procedia 2015 v tlači) Shear Failure of Amorphous Alloy at Nanoindentation (Powder Metallurgy Progress Vol )

Nanoindentation  Useful technique for measuring the mechanical properties of small volume of materials and provides insights into mechanisms of metallic glass deformation.  Interesting feature of inhomogeneous deformation during nanoindentation of metallic glasses are continuous serrations (serial pop-ins) in P-h curve.  Serrations are associated with shear band nucleation and their propagation.

Experimental materials and methods  Three amorphous ribbons: Fe 40 Ni 40 B 20 [at.%] Cu 47 Ti 35 Zr 11 Ni 6 Si 1 Zr 65 Cu 17.5 Ni 10 Al 7.5  Nanoindentation equipment: MTS Nanoindenter XP  Loading rates to maximum load 250 mN: 100 mN.s mN.s -1 1 mN.s mN.s mN.s -1  Type of indenter: Cube corner indenter  Observation of indents under SEM

P-h nanoindentation curves and indents under SEM Fe 40 Ni 40 B 20 Cu 47 Ti 35 Zr 11 Ni 6 Si 1 Zr 65 Cu 17.5 Ni 10 Al 7.5

Scheme of the estimation of the plastic and elastic contribution to the deformation at the individual pop-in event Discrete plasticity ratio:

Dependences of the discrete plasticity ratio as a function of the loading rate at indentation for different metallic glasses ‐ For all studied alloy compositions the discrete plasticity ratio parameter reaches the values from 0.4 to 0.8. ‐ For Fe-based alloy the tendency to the decrease of this parameter with the increase of loading rate can be suggested. ‐ For Cu- and Zr-based alloys the conclusions about the deformation rate influence on the discrete plasticity ratio cannot be made.

Indents under SEM Fe 40 Ni 40 B mN.s mN.s -1 1 mN.s mN.s mN.s -1

Dependences of thickness of individual plates on the distance from pile-up tip

The scheme of the formation of shear bands at nanoindentation

Conclusion Nanoindentation experiments have revealed the presence of the deformation discontinuities on all three types of amorphous alloys (Fe 40 Ni 40 B 20, Cu 47 Ti 35 Zr 11 Ni 6 Si 1 and Zr 65 Cu 17.5 Ni 10 Al 7.5 ) at loading rates up to 10 mN.s -1. These discontinuities on the P-h curves start at the load up to 50 mN. As the indent penetrates deeper, the discontinuities are more pronounced. The deformation discontinuities were analyzed using discrete plasticity ratio concept. The observation of indent region morphology does not show a direct connection between the presence of pop-ins and the shear band morphology. The measured effective shear band density varies from 8-50 μm -1.

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