In-situ TEM observation of dissolution-enhanced dislocation emission, motion and the nucleation of SCC for Ti-24Al-11Nb alloy in methanol

Journal Article · Wed Jan 15 00:00:00 EST 1997 · Scripta Materialia

DOI:https://doi.org/10.1016/S1359-6462(96)00368-5· OSTI ID:417912

Gao, K W; Chu, W Y; Wang, Y B; Hsiao, C M ^[1]

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1. Univ. of Science and Technology Beijing (China). Dept. of Materials Physics

Many experiments have showed that anodic polarization can facilitate ambient creep for various metals and alloys. Anodic polarization can decrease the yield strength, and enlarge the plastic zone on the surface ahead of a loaded crack tip. The density of dislocations in a region very close to the fracture surface of SCC was much higher than that far away from the fracture surface. All of these experiments showed that anodic dissolution facilitated the localized plastic deformation. Up to now, however, direct proof of anodic dissolution or corrosion-enhanced dislocation emission, multiplication and motion is lacking. Using a special constant deflection device, the dislocation configuration change ahead of a loaded crack tip before and after anodic dissolution together with the initiation of SCC for Ti-24Al-11Nb alloy in methanol can be in-situ observed in TEM. The results showed that the localized anodic dissolution could facilitate dislocation emission, multiplication and motion and SCC with size of nanometers would initiate in the dislocation-free zone (DFZ) or at the original crack tip after the dissolution-enhanced dislocation emission and motion reached a critical condition.

• OSTI ID: 417912
• Journal Information: Scripta Materialia, Vol. 36, Issue 2; Other Information: PBD: 15 Jan 1997
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
TITANIUM ALLOYS
DISLOCATIONS
STRESS CORROSION
FRACTURE PROPERTIES
ALUMINIUM ALLOYS
NIOBIUM ALLOYS
TRANSMISSION ELECTRON MICROSCOPY
CRACKS
DISSOLUTION
CRACK PROPAGATION
STRESSES
STRESS INTENSITY FACTORS
EXPERIMENTAL DATA