Mechanical properties of aluminized CoCrAlY coatings in advanced gas turbine blades

Technical Report · Tue Jul 01 04:00:00 EDT 1997

DOI:https://doi.org/10.2172/505288· OSTI ID:505288

Kameda, J; Bloomer, T E ^[1]; Sugita, Y; Ito, A ^[2]; Sakurai, S ^[3]

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1. Ames Lab., IA (United States)
2. Chuba Electric Power Co., Nagoya (Japan). Electric Power R and D Center
3. Hitachi Ltd. (Japan). Mechanical Engineering Research Lab.

The microstructure/composition and mechanical properties (22-950 C) in aluminized CoCrAlY coatings of advanced gas turbine blades have been examined using scanning Auger microprobe and a small punch (SP) testing method. Aluminized coatings were made of layered structure divided into four regimes: (1) Al enriched and Cr depleted region, (2) Al and Cr graded region, (3) fine grained microstructure with a mixture of Al and Cr enriched phases and (4) Ni/Co interdiffusion zone adjacent to the interface SP tests demonstrated strong dependence of the deformation and fracture behavior on the various coatings regimes. Coatings 1 and 2 showed higher microhardness and easier formation of brittle cracks in a wide temperature range, compared to coatings 3 and 4. The coating 3 had lower room temperature ductility and conversely higher elevated temperature ductility than the coating 4 due to a precipitous ductility increase above 730 C. The integrity of aluminized coatings while in-service is discussed in light of the variation in the low cycle fatigue life as well as the ductility in the layered structure.

• Research Organization: Ames Lab., IA (United States)
• Sponsoring Organization: USDOE Office of Energy Research, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 505288
• Report Number(s): IS-M--869; CONF-970806--2; ON: DE97006803
• Country of Publication: United States
• Language: English

Related Subjects

20 FOSSIL-FUELED POWER PLANTS
36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
CHROMIUM ALLOYS
COBALT BASE ALLOYS
EXPERIMENTAL DATA
GAS TURBINES
MECHANICAL PROPERTIES
MICROSTRUCTURE
PROTECTIVE COATINGS
TURBINE BLADES
YTTRIUM ADDITIONS