Effect of La addition on glass-forming ability and stability of mechanically alloyed Zr–Ni amorphous alloys

Abstract

In this study, the role of La in the microstructural evolution of Zr66.7−xNi33.3Lax (x=1, 3, 5at.%) alloys during mechanical alloying has been investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The results show that the single amorphous phase of Zr–Ni–La can be obtained through mechanical alloying. The minor La addition can improve the glass forming ability of Zr–Ni–La, enhance the mechanical stability of the amorphous phase against the mechanically induced crystallization and lead to an altered crystallization mode of Zr–Ni alloy. Moreover, the stability of the Zr–Ni–La amorphous phase decreases with further increasing La content. The best effect is obtained for the Zr65.7Ni33.3La1 alloy. Additionally, the effect of La addition in contrast with the small atomic size C addition plays a more significant role in promoting the stability of the amorphous phase. In addition, the reasons of La addition effect on GFA and stability have also been discussed from three factors of negative heat of mixing, distance between neighboring atoms and atomic size mismatch, respectively.