Fracture toughness study of new Zr-based Be-bearing bulk metallic glasses

摘要

Three new compositional variants of the Zr-Ti-Be-LTM (late transition metal) family of metallic glasses are discussed. Thermal stability, DELTAT=T_x-T_g, was increased from 82 deg for Zr_41.2Ti_13.8Cu_12.5Ni_10Be_22.5 (Viterloy 1) to 141 deg for Zr_44Ti_11Cu_20Be_25. It is found that fracture toughness is the most distinguishing parameter characterizing the alloys in contrast to other mechanical properties. Quaternary alloys consistently had fracture toughness values exceeding 80 MPa m~(1/2), while for Vitreloy 1 K_Q=48.5 MPa m~(1/2) with a large amount of scatter. Adding iron reduced the fracture toughness to 25 MPa m~(1/2).