Mg–Ni–Gd–Ag bulk metallic glass with improved glass-forming ability and mechanical properties

The improvement of glass-forming ability (GFA) and mechanical properties by using Ag to substitute Mg in the Mg–Ni–Gd bulk metallic glass (BMG) were studied. The Mg69Ni15Gd10Ag6 bulk metallic glass (BMG) could be cast into glassy rod up to 7 mm. The activation energies of Mg69Ni15Gd10Ag6 metallic glass were calculated by the Kissinger’s method to be Eg = 2.24 eV, Ex = 1.65 eV, Ep1 = 1.36 eV, Ep2 = 1.59 eV, Ep3 = 1.26 eV and Ep4 = 1.99 eV. The compressive fracture strength and the plastic strain of Mg69Ni15Gd10Ag6 BMG reached 846 MPa and 0.37% respectively.

The element Mg in the Mg75Ni15Gd10 BMG was substituted with the element Ag to cause a significant improvement of GFA. The diameter of fully glassy rod obtained by copper mold inject casting was increased to 7 mm of Mg69Ni15Gd10Ag6 alloy from 3 mm of Mg75Ni15Gd10 alloy.Figure optionsDownload as PowerPoint slideHighlights
► In this paper, we report the effect of partial substitution of Ag for Mg on the glass-forming ability (GFA), mechanical properties in the Mg–Ni–Gd–Ag alloy system.
► The critical glass formation diameter increases from 3 mm in Mg75Ni15Gd10 to 7 mm in Mg69Ni15Gd10Ag6 alloy.
► Large difference in atomic size and in mixing enthalpy is helpful to improve the GFA and mechanical properties of Mg75Ni15Gd10 alloy.
► The activation energies of Mg69Ni15Gd10Ag6 metallic glass were calculated by the Kissinger’s method to be Eg = 2.24 eV, Ex = 1.65 eV, Ep1 = 1.36 eV, Ep2 = 1.59 eV, Ep3 = 1.26 eV and Ep4 = 1.99 eV.
► The compressive fracture strength and the plastic strain of Mg69Ni15Gd10Ag6 BMG reached 846 MPa and 0.37% respectively.