Accession Number : AD0809387

Title :   ELEVATED TEMPERATURE DUCTILITY MINIMA AND CREEP STRENGTHENING OF COATED AND UNCOATED COLUMBIUM ALLOYS.

Descriptive Note : Final rept. 1 Sep 65-30 Aug 66,

Corporate Author : BATTELLE MEMORIAL INST COLUMBUS OH

Personal Author(s) : Allen, B. C. ; Barlett, E. S. ; Wilcox, B. A.

Report Date : FEB 1967

Pagination or Media Count : 73

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. (Author)

Descriptors :   (*NIOBIUM ALLOYS, DUCTILITY), COATINGS, CREEP, MICROSTRUCTURE, SUBSTRATES, STRAIN(MECHANICS), TENSILE PROPERTIES.

Subject Categories : Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE