Nanocrystalline formation in Zr_52.5Cu₂₇Ni_5.5 Al₂₂Nb₃ amorphous alloy and the effect on compress mechanical properties

Bulk Zr_52.5Cu_30-xNi_5.5 Al₁₂Nb_x (x = 0, 3) metallic glass was prepared by using a copper mold casting method. When x = 0, the sample structure is amorphous; when x = 3, the sample consists of the particles rich in Zr and Nb with a size of 20 nm and dispersed homogeneously in amorphous matrix, in which some bcc Zr-Nb solid solution nanoparticles of 5 nm were embedded. The toughness of Zr_52.5Cu₂₇Ni_5.5 Al₁₂Nb₃ amorphous alloy was significantly improved as compared with the Zr_52.5Cu₃₀Ni_5.5Al₂₂ alloy with monolithic amorphous structure. The compress fracture strength (σ_f) is 1600 MPa at x = 0, and increases up to 1964 MPa at x = 3. These nanocrystallines and the regions rich in Zr and Nb acted as the resistant medium against shear deformation, leading to the increase in the toughness. The deformation mode of sample changes from single slip (when x = 0) to multiple slip (when x =3), and a number of slip bands occur crosswise and interfere each other, so that the brittle failure of inhomogeneous deformation can be retarded.