Crystallization, mechanical and corrosion properties of Zr-Cu-Ni-Al-Nb bulk glassy alloys

Abstract

Zr65-xCu17.5Al7.5Ni10Nbx bulk metallic glasses (BMGs) with x=0, 2 and 5 were prepared by water-cooled cop per mold casting. X-ray diffraction and differential scanning calorimetry reveal ed that the addition of Nb changes crystallization pathway of the base alloy and promotes an initial formation of icosahedral quasicrystals. The mechanical prop erties of the BMGs prepared were measured with MTS in a mode of quasi-static com pression. It was found that the addition of an appropriate amount of Nb signific antly enhances the compression strength and plastic strain with the maximum valu e of σb =1741MPa and εp= 5.0% for the BMG containing 5at % Nb. In addition, the corrosion behavior of the BMGs was investigated in 3% NaC l aqueous solution by electrochemical measurements. It showed that the BMGs with different compositions are all spontaneously passivated with passive current de nsity of 10-6—10-5 A/cm2, which is three order of magnitude lower than that of 1Cr18Ni9Ti stainless steel. The corrosion resis tance of the BMGs can be further enhanced with the addition of Nb, as indicated by the increase in pitting potential with the increase of Nb content.