Nucleation of shear bands in amorphous alloys

John H. Perepezko, Seth D. Imhoff, Ming Wei Chen, Jun Qiang Wang, Sergio Gonzalez

    Research output: Contribution to journalArticlepeer-review

    51 Citations (Scopus)

    Abstract

    The initiation and propagation of shear bands is an important mode of localized inhomogeneous deformation that occurs in a wide range of materials. In metallic glasses, shear band development is considered to center on a structural heterogeneity, a shear transformation zone that evolves into a rapidly propagating shear band under a shear stress above a threshold. Deformation by shear bands is a nucleation-controlled process, but the initiation process is unclear. Here we use nanoindentation to probe shear band nucleation during loading by measuring the first pop-in event in the load-depth curve which is demonstrated to be associated with shear band formation. We analyze a large number of independent measurements on four different bulk metallic glasses (BMGs) alloys and reveal the operation of a bimodal distribution of the first pop-in loads that are associated with different shear band nucleation sites that operate at different stress levels below the glass transition temperature, Tg. The nucleation kinetics, the nucleation barriers, and the density for each site type have been determined. The discovery of multiple shear band nucleation sites challenges the current view of nucleation at a single type of site and offers opportunities for controlling the ductility of BMG alloys.

    Original languageEnglish
    Pages (from-to)3938-3942
    Number of pages5
    JournalProceedings of the National Academy of Sciences of the United States of America
    Volume111
    Issue number11
    DOIs
    Publication statusPublished - 2014 Mar 18

    Keywords

    • Plastic deformation
    • Stochastic analysis

    ASJC Scopus subject areas

    • General

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