Effect of Nb content on the microstructure and mechanical properties of Zr-Cu-Ni-Al-Nb glass forming alloys

(Zr₆₅Al₁₀Ni₁₀Cu₁₅) _100-xNb_x glass forming alloys with Nb contents ranging from 0 to 15 at.% were prepared by water-cooled copper mould cast. The alloys with different Nb contents exhibited different microstructures and mechanical properties. Unlike the monolithic Zr₆₅Al₁₀Ni ₁₀Cu₁₅ bulk metallic glass, only a few primary bcc β-Ti phase dendrites were found to distribute in the glassy matrix of the alloys with x = 5. For alloys with x = 10, more β-phase dendrites forms, together with quasicrystalline particles densely distributed in the matrix of the alloys. For alloys with x = 15, the microstructure of the alloy is dominated by a high density of fully developed β-phase dendrites and the volume fraction of quasicrystalline particles significantly decreases. Room temperature compression tests showed that the alloys with x = 5 failed at 1793 MPa and exhibited an obvious plastic strain of 3.05%, while the other samples all failed in a brittle manner. The ultimate fracture strengths are 1793, 1975 and 1572 MPa for the alloys with x = 0, 10 and 15 at.% Nb, respectively. © 2005 Elsevier B.V. All rights reserved.