Formation of novel TRIP-ductilized bulk metallic glass composites by manipulating nucleation kinetics via minor alloying

A series of conical bulk metallic glass composites (BMGCs) with compositions of Zr₄₇Cu_47−xAl₅Ag₁Ga_x (x = 0, 1, 2, 4; at%) were synthesized using the minor alloying method to investigate the effect of Ga addition on the glass-forming ability (GFA), microstructure uniformity and mechanical properties. The results showed that the addition of less than 2 at% Ga could effectively promote the base alloy’s GFA, and in turn, the critical forming diameters of the BMGCs which exhibited evenly distributed B2-CuZr spheroids embedded in the glass matrix. This is attributed to the increase in nucleation energy barrier owing to the minor Ga addition that reduces the thermodynamic driving force for the B2 formation, thus leading to reduced nucleation rates, smaller volume fractions of B2, and enlarged inter-spacings between B2 spheroids while suppressing the agglomeration of B2 spheroids in the BMGCs. As such, the 1 at% Ga addition was found to yield an optimal BMGC which possessed good compressive plasticity with a considerably large uniform deformation strain up to 8%. This study has important implications for designing novel BMGCs by manipulating the nucleation kinetics via minor alloying.