Effect of Chloride Ion Concentration on the Fatigue Crack Growth Rate of a Zr55Al10Ni5Cu30 Bulk Metallic Glass

The effect of chloride ions on the fatigue crack growth rates of a Zr55Al10Ni5Cu30 bulk glassy alloy has been investigated by using a 3-point bending test method in NaCl solutions and phosphate buffered (PCA) solutions containing 0.1–0.5 kmol/m3 NaCl at room temperature. The crack growth rates increase with increasing chloride content, although the crack growth behavior in PCA + 0.1 kmol/m3 NaCl is almost the same as that in PCA without NaCl or in air. Another interesting feature is that the crack growth rates in the PCA + NaCl are lower than those in NaCl of the same content. The adsorbed phosphate ions at the crack tip of the specimen may prevent the adsorption of chloride ions, resulting in the decrease in the growth rates. SEM results reveal that the remarkably different fractography is obtained for the fatigue crack growth region in aqueous solutions containing the certain amount of chloride ions. [doi:10.2320/matertrans.MRP2007085