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

Abstract

The oxidation of tantalum and Ta-10% W with aluminum/aluminide 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.

Document Details

Document Type
Technical Report
Publication Date
Apr 01, 1966
Accession Number
AD0485023

Entities

People

  • Per Kofstad

Tags

DTIC Thesaurus Topics

  • Aluminides
  • Aluminum
  • Diffraction
  • Electrons
  • Measurement
  • Microprobes
  • Oxidation
  • Oxidation Resistance
  • Resistance
  • Tantalum
  • X Rays
  • X-Ray Diffraction

Fields of Study

  • Materials science

Readers

  • Surface Engineering/Surface Coating Technology.

Technology Areas

  • Microelectronics