The effect of impurities in zirconium on the formation and mechanical properties of Zr55Cu30Al10Ni5 metallic glass

Abstract

Minor alloying has been developed as an effective method to modify and optimize various properties of bulk metallic glasses (BMG). In this work, as inevitable minor alloying elements, two major impurities, hafnium (Hf) and oxygen (O) were quantitatively confirmed to co-exist in two zirconium (Zr) raw materials with different grades of impurities. The effects of these two impurities on the thermal properties, crystallization behavior, glass-forming ability (GFA), and mechanical properties of the nominal Zr55Cu30Al10Ni5 BMG were systematically studied. The O impurity was found to promote the formation of the Al5Ni3Zr2 intermetallic compound phase, which could account for the poor GFA, thermal stability, and plasticity associated with BMGs with higher O content in the Zr raw material. In contrast, although the impurity of Hf has a much higher content than O, a negligible effect of Hf on the Zr55Cu30Al10Ni5 BMG was revealed. These findings were further confirmed by deliberately adding extra O and Hf with designed contents into the Zr55Cu30Al10Ni5 BMG. Our results clarify the effects of different impurities in Zr raw materials on the Zr-based BMG and will help guide industrial production and applications of Zr-based BMGs.