Improving the Corrosion Resistance of NiNb-Based Bulk Metallic Glass through the Hot Compression

Abstract

This paper aims to study and evaluate the corrosion resistance of Ni55Nb45 and Ni55Nb35Co5Zr5 bulk metallic glasses (BMGs) in an environment similar to proton exchange membrane fuel cells. Moreover, the hot compression process was carried out to find the effects of a thermomechanical treatment on the corrosion resistance. The X-ray diffraction (XRD) test indicated that the hot compression process led to formation of crystalline species in both samples; however, it was more pronounced in the Ni55Nb35Co5Zr5 alloy. It is suggested that the minor addition of Zr and Co facilitated the crystallization in the material. The polarization test unveiled that the hot compression deteriorated the corrosion resistance of the Ni55Nb45 alloy through the introduction of anomalous chemical interfaces. On the other hand, the hot deformation affected the Ni55Nb35Co5Zr5 alloy in a positive way, so that the corrosion behavior improved compared with its fully glassy state. It is suggested that the hot deformation induces some NiNb crystalline constituencies in the microstructure of Ni55Nb35Co5Zr5 BMG, leading to the enrichment of glassy matrix from Zr/Co constituencies and the enhancement of corrosion resistance.