TEM Studies of Shear Bands in a Bulk Metallic Glass Based Composite

Abstract

<jats:p>In 1980’s the discovery of multicomponent systems with exceptional glass forming ability enabled the synthesis of metallic glasses at relatively low cooling rates, 10<jats:sup>−1</jats:sup> — 10<jats:sup>2</jats:sup> K/s and at a larger thicknesses. Bulk metallic glasses normally have very high yield stress, σ<jats:sub>y</jats:sub> = 0.02 · Y (Y is Young’s modulus), high elastic limit of about 2%, but fail with very little global plasticity, typically along a localized shear band at a 45 degree angle with respect to the applied stress.</jats:p><jats:p>The material studied in the present work is a two-phase Zr<jats:sub>56.3</jats:sub>Ti<jats:sub>13.8</jats:sub>Cu<jats:sub>6.9</jats:sub>Ni<jats:sub>5.6</jats:sub>Nb<jats:sub>5.0</jats:sub>Be<jats:sub>12.5</jats:sub> alloy,prepared by in-situ processing. The alloy consists of amorphous and crystalline phases. In-situ TEM straining (tensile) experiments were performed at room temperature in JEOL 4000EX operating at 300kV. The experiments were carried out in the Center for Microanalysis of Materials in the University of Illinois at Urbana-Champaign. The goal of the study was to understand the deformation mechanisms of such composite material.</jats:p>