Vickers hardness and compressive properties of bulk metallic glasses and nanostructure-dendrite composites

Abstract

The compressive properties and the Vickers hardness of Cu-, Fe-, Mg-, and Zr-based monolithic bulk metallic glasses (BMGs) as well as Ti-based nanostructure-dendrite composites were investigated and compared. The monolithic BMGs exhibit nearly the same yield strength σ y and fracture strength σf but poor plasticity. The Vickers hardness HV of the monolithic BMGs follows the empirical relationship HV/3 ≈σy ≈σf. The Ti-based composites yield at a relatively low stress level (less than 850 MPa) but fail at a very high fracture stress (∼ 2 GPa) and exhibit a large strain hardening ability. Accordingly, the Vickers hardness HV of the Ti-based nanostructure-dendrite composites obeys the relationship σy <HV/3 <σf. Based on these results, the relationship between the Vickers hardness and the compressive properties of the investigated materials will be discussed by taking the yield and fracture strength (σ y and σf), the strain hardening exponent n, and the elastic and plastic energy stored upon deformation (δΕ and δP) into account.