Effect of annealing on the devitrification behavior and mechanical properties of rapidly quenched Ce-based glassy alloys

Abstract This study deals with the effect of controlled crystallization of melt spun Ce 75 Al 25 − x Ga x (x = 0, 2, 4 and 6 at.%) and Ce 60 Cu 25 Al 15 − x Ga x (x = 0, 1, 2 and 4 at.%) metallic glasses on the formation of nano-composites. It has been found that the substitution of Ga significantly affects the devitrification behavior of these alloys. The Ce 75 Al 25 − x Ga x alloys with x = 0 shows the formation of hexagonal phase (AlCe 3 type) while the alloys with x ≥ 2 give rise to the formation of tetragonal phase (Al 2 CeGa 2 type). Contrary to this, for the Ce 60 Cu 25 Al 15 − x Ga x alloys, hexagonal phase of AlCeCu type for x = 0 transforms to hexagonal phase of Al 2 Cu 3 Ce type for x ≥ 1. The indentation behavior of nano-composites permitted us to understand the nature of microhardness, yield strength and strain hardening constant. They are compared for the above two alloy systems. The load dependent hardness values of annealed ribbons of Ce 75 Al 19 Ga 6 and Ce 60 Cu 25 Al 13 Ga 2 alloys have been found to be ~ 2.80 GPa and ~ 2.96 GPa, respectively. The absence of cracks around the indentation area up to 200 g of load for Ce 60 Cu 25 Al 15 − x Ga x alloys suggests better capability to resist crack propagation in comparison to Ce 75 Al 25 − x Ga x alloys. Latter display cracks at 200 g load. The formation of shear bands around the periphery of the indenter has been observed. The number of visible shear bands in a given area for the Ce 75 Al 25 − x Ga x alloys is higher in comparison to those of Ce 60 Cu 25 Al 15 − x Ga x alloys. The values of yield strength and Meyer exponent of these alloys are also compared.