Accession Number:

AD0485023

Title:

MECHANISMS OF PROTECTION AND FAILURE IN ALUMINIDE COATED TANTALUM AND TANTALUM BASE ALLOYS.

Descriptive Note:

Summary rept. Oct 64-Sep 65,

Corporate Author:

CENTRAL INST FOR INDUSTRIAL RESEARCH OSLO (NORWAY)

Personal Author(s):

• Kofstad, Per

Report Date:

1966-04-01

Pagination or Media Count:

51.0

Abstract:

The oxidation of tantalum and Ta-10 W with aluminumaluminide coatings and tantalum with Al-Cr coatings have been studied in the temperature range 800-1600 C and at oxygen pressures ranging from 0.1 torr to 1 atm. O2. The experimental studies comprise thermogravimetric oxidation rate measurements, x-ray diffraction studies, metallographic investigation, and electron microprobe analysis studies. The unalloyed coatings on Ta and Ta-10 W provided at 0.1 torr O2 excellent oxidation resistance at temperatures above 1100 C, but at 800-1000 C breakaway oxidation occurred. The protectivity is provided by an alpha-Al2O3 layer. At 1 atm. O2 the unalloyed coatings failed at all temperatures. The interdiffusion of aluminum and tantalum leads to the formation of TaAl3, Ta3Al, the Ta-Al phase with approximately 10 wt Al, and a Ta-Al phase with approximately 20 wt Al.

Descriptors:

• *TANTALUM ALLOYS
• *TANTALUM
• ALUMINUM COATINGS
• CORROSION RESISTANCE
• OXYGEN
• TEMPERATURE
• THERMOGRAVIMETRIC ANALYSIS
• X RAY DIFFRACTION
• TUNGSTEN ALLOYS
• PROTECTIVE TREATMENTS
• DIFFUSION
• PRODUCTION
• ALUMINUM ALLOYS
• PHASE STUDIES
• CHROMIUM
• MIXTURES
• OXIDES
• ALUMINUM COMPOUNDS
• CHROMIUM COMPOUNDS
• PROBES
• METALLOGRAPHY

Subject Categories:

• Properties of Metals and Alloys

Distribution Statement:

APPROVED FOR PUBLIC RELEASE