Metallography of Aluminide Coatings

Abstract

The Corrosion Control group at ARL has commenced a programme for evaluating protective coatings for gas turbine blades currently used by the RAAF (work previously performed at MRL). To enable examination and evaluation of metallographic specimens (with particular attention given to surface features), techniques have been developed for sample preparation and microstructural etching. In developing these techniques, Allison T-56 turbine engine blades cast from a nickel-based superalloy (IN 738) and coated with nickel aluminide were sectioned. The nickel aluminide coating applied by a high-activity pack-cementation process to the outer surface of the blades, imparts oxidation/corrosion resistance to the substrate superalloy. Metallographic procedures were developed with an aim to minimise edge rounding and highlight the detailed microstructure by selective etching.

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Document Details

Document Type
Technical Report
Publication Date
May 01, 1991
Accession Number
ADA243000

Entities

People

  • P. Rohan

Tags

Communities of Interest

  • Air Platforms
  • C4I
  • Space

DTIC Thesaurus Topics

  • Aircrafts
  • Chemistry
  • Coatings
  • Corrosion Resistance
  • Electroplating
  • Engineering
  • Films
  • Gas Turbine Blades
  • Gas Turbines
  • Grain Boundaries
  • Materials
  • Materials Engineering
  • Nickel Aluminide
  • Protective Coatings
  • Substrates
  • Turbine Blades
  • Turbines

Fields of Study

  • Materials science

Readers

  • Powder metallurgy of Titanium alloys.
  • Structural Health Monitoring of Composite Structures.
  • Surface Engineering/Surface Coating Technology.