Si-alloying effect on glass-forming ability and crystallization behavior of Zr72.5Al10Fe17.5 metallic glass

•0.2 at.% Si addition improved the glass-forming ability and thermal stability of Zr72.5Al10Fe17.5.•Glass forming ability of (Zr72.5Al10Fe17.5)100-xSix was related with atomic packing density.•Thermal stability of alloys with the Si addition of x≤0.5 was negatively correlated with its free volume concentration.•The variation of crystallization activation with Si addition was responsible for the two-stage crystallization.