Elevated Temperature Ductility Minima and Creep Strengthening of Coated and Uncoated Columbium Alloys
Abstract
In Phase 1 an investigation was made of factors affecting the tensile ductility minimum behavior of coated columbium alloys in air in the intermediate temperature range 700-1100 C. In the case of TRW Cr-Ti-Si coated Cb-10W and Cb-10W-2.5Zr(Cb-752 Alloy), contamination and embrittlement by air at the base of coating cracks is the major factor responsible for loss of ductility. Apparent mechanical interaction between coating and substrate palys a smaller role, but becomes more important with decreasing substrate thickness. The presence of zirconium and dynamic strengthening of the substrate have relatively little effect on ductility. A study of dynamic strengthening during creep of Cb-10W-2.5Zr and Cb-10W was the objective of Phase 2. All creep testing was done in a vacuum of 10 to the minus 6th power torr and under constant stress conditions. The temperature range of interest was 800-1200 C. In long-time creep tests, the usual dynamic strengthening process in the Cb-10W-2.5Zr alloy was complicated by additional hardening due to internal oxidation. The Cb-10W-2.5Zr alloy was considerably stronger in creep than Cb-10W. The possible strengthening effects of Zr are discussed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1967
- Accession Number
- AD0809387
Entities
People
- B. A. Wilcox
- B. C. Allen
- E. S. Barlett
Organizations
- Battelle Memorial Institute