The Effect of Oxygen on the Structure and Mechanical Behavior of Aged Ti-8 WT. %Al.
Abstract
It is shown that for a Ti-8 wt.%Al alloy aged at a temperature high in the two-phase region (695C) to precipitate the ordered alpha 2 phase, an increase in oxygen content from 600 ppm to 12 ppm increases the yield strength by approximately 10% and decreases the fracture strain from 20 to 1% elongation at room temperature. The fracture mode is changed from dimpled rupture to cleavage. It is demonstrated that oxygen additions alter the position of the alpha/alpha + alpha 2 coherent solvus, resulting in formation of coherent alpha 2 in specimens containing approximately or more than 1000 ppm oxygen aged at 695C. For a given aging time the volume fraction of alpha 2 increases with increasing oxygen up to 1300 wt.ppm and then levels off. The changes in mechanical behavior are attributed to the presence of alpha 2. The experimental evidence suggests that oxygen partitions preferentially into alpha 2.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 31, 1974
- Accession Number
- ADA011367
Entities
People
- C. J. Mcmahon Jr.
- D. P. Pope
- J. C. Williams
- J. Y. Lim
Organizations
- University of Pennsylvania