PLASTIC PROPERTIES AND FRACTURE OF TITANIUM-ALUMINUM ALLOYS.
Final rept. 27 May 69-26 Jan 70,
PENNSYLVANIA UNIV PHILADELPHIA SCHOOL OF METALLURGY AND MATERIALS SCIENCE
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A program was conducted to determine the effects of Al content and Ti3Al precipitation on the micro- and macroplastic behavior of low interstitial Ti-Al alloys, and also to investigate the effects of Al content and Ti3Al on the susceptibility to stress corrosion cracking in a methanol-0.61 HCl-1.0 H2O environment. The Hall-Petch parameter k sub y, and indication of degree of plastic anisotropy, remained relatively constant for solution treated alloys of compositions up to 6 Al but increased significantly at the 8 Al level and in aged Ti-6 Al and Ti-8 Al alloys. This increase in k sub y is attributed to the decrease in propensity for cross-slip at higher Al alloys, particularly when aged to form Ti3Al. The decrease in cross-slip is apparent in the change in slip mode, as observed by transmission electron microscopy, with increasing planarity of slip observed to accompany aluminum additions. In the aged alloys deformation, observed after 4 tensile strain, was confined to narrow, intense slip bands. The influence of Ti3Al on both the macro- and micro-yield stresses is athermal. Author
- Properties of Metals and Alloys