Analysis of stress–corrosion interactions for bulk metallic glasses

(Analyse mechanisch–korrosiver Wechselwirkungen für massive metallische Gläser)

Due to their excellent mechanical properties combined with high glass forming ability Zr-based bulk metallic glasses, in particular, generated significant interest for applications under high loading conditions. However, corrosion reactions inherent in many aqueous media may act in synergy with mechanical damage processes and lead to environmentally induced degradation. Fundamental studies revealed interactions between shear band formation and corrosion initiation owing to local chemical and structural changes in the otherwise homogeneous glassy phase. On the example of Zr52.5Cu17.9Al10Ni14.6Ti5 (Vitreloy 105), stress corrosion cracking phenomena in a chloride-containing electrolyte under three-point bending conditions are investigated. Pits were identified as initiation sites to cracking. Features corresponding to mechanical brittle cracking, shear banding and dissolution assisted cracking were found on the fracture surface. A mechanism is proposed in which crack tip blunting is attributed to shear banding and re-sharpening to preferential anodic dissolution along shear bands. 

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