Investigation of the effects of Al on the glass forming ability of Zr-Cu-Ni-Al alloys through their solidification characteristics

Abstract The alloying addition was widely and effectively used to develop the new BMGs and improve the glass formation ability (GFA) of the BMG materials. In this study, using the Zr-Cu-Ni-Al system as a mold, the effects of Al addition on both the microstructural evolution and glass forming ability were studied experimentally. The results indicate that when the amount of added Al is less than 10 at. % in the present alloys, Al is dissolved into the phases of ZrCu and Zr 2 Cu, and does not change the phase competition. However, both the kinetic and thermodynamic conditions for the amorphous formation are enhanced with increasing Al content. The rods of at least 10 mm diameter can be cast fully amorphous for the alloy (Zr 57.4 Cu 33.3 Ni 9.3 ) 90 Al 10 . When Al content is further increased to 12% or more, some Al-rich Zr 51 Cu 28 Al 21 (τ 3 ) and Zr 38 Cu 36 Al 26 (τ 5 ) phases precipitate firstly during solidification, thereby deteriorating the GFA of alloys. These findings give a new perspective to apply alloying addition in a way that enhances the GFA.