The effect of microalloying on thermal stability and corrosion resistance of Cu-based bulk metallic glasses

(Cu47Zr11Ti34Ni8)99.5M0.5 (M = 0, Cr, Mo and W) bulk metallic glasses (BMGs) with diameter of 3 mm were prepared by water-cooled copper mold casting. The effect of the addition of a small amount of Cr, Mo or W on thermal property and corrosion resistance of the base BMG (i.e., Cu47Zr11Ti34Ni8) was investigated by means of XRD, DSC, electrochemical polarization and weight loss measurements. It was found that the addition of the elements led to a significant decrease in glass transition temperature (Tg) and crystallization temperature (Tx) of the base BMG. As the results, the supercooled liquid region, ΔTx = Tx1 − Tg, slightly decreased for the BMG containing Cr, but increased for the BMGs containing Mo and W with a maximum value of 66 K for (Cu47Zr11Ti34Ni8)99.5W0.5 bulk metallic glass. Electrochemical measurements on various Cu-based BMGs were conducted in 1N H2SO4 and 1N NaOH aqueous solutions, respectively, at room temperature. It showed that the BMGs with a small amount of Cr, Mo or W exhibited a superior corrosion resistance in the two electrolytes as compared with the base alloy. (Cu47Zr11Ti34Ni8)99.5Mo0.5 BMG exhibited the greatest corrosion resistance, as indicated by the lowest passive current density and the lowest corrosion rate. The effect of the element addition on thermal stability and corrosion behavior has been tentatively discussed.