Effects of Cu addition on the glass forming ability and corrosion resistance of Ti-Zr-Be-Ni alloys

The Ti-based bulk metallic glasses (BMG) with high Ti content (>50 at.%) have attracted wide attention for their outstanding mechanical properties, despite their glass forming ability (GFA) is still relatively poor. Here the (Ti55Zr15Be20Ni10)(100-x)Cu-x(x = 2, 4, 6, 8 and 10 at.%) BMGs were designed and prepared by copper mold casting. The critical diameter of the original alloy could be enhanced from 5 mm to 10 mm with the Cu addition of 4 at.%, which is the first reported centimeter-sized Ti-based BMG with Ti content more than 52 at.%. In addition, all the as-prepared BMGs exhibited higher yield strength (above 2000 MPa). And the supercooled liquid range of the as-prepared Ti-based BMGs were enlarged from 35 K to 74 K by Cu addition. Electrochemical measurements showed that the BMGs with Cu addition of 0-6 at.% exhibited much higher pitting potentials (over 573 mV/SCE) than that of 304 stainless steel (304SS) in 3.5 wt% NaCl aqueous solution. And The XPS analysis revealed that the Cu addition might lead to the enrichment of Cu and the deficiency of Ti, Zr, Ni elements in passive film, which could induce the worse corrosion resistance of the Ti-based BMGs with high Cu content. The results indicate that the developed Ti-based BMGs possess good GFA, mechanical properties and corrosion resistance. (C) 2017 Elsevier B.V. All rights reserved.