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

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 σ_f but poor plasticity. The Vickers hardness H_V of the monolithic BMGs follows the empirical relationship H_V/3 ≈σ_y ≈σ_f. 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 H_V of the Ti-based nanostructure-dendrite composites obeys the relationship σ_y <H_V/3 <σ_f. 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 σ_f), the strain hardening exponent n, and the elastic and plastic energy stored upon deformation (δ_Ε and δ_P) into account.