Mechanical properties of aluminized CoCrAlY coatings in advanced gas turbine blades [report]

J. Kameda, T.E. Bloomer, Y. Sugita, A. Ito, S. Sakurai
1997 unpublished
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, (I) Al enriched and Cr depleted region, (11) Al and Cr graded region, (III) h e grained microstructure with a mixture of Al and Cr enriched phases and (IV) Ni/Co interdasion zone adjacent to the
more » ... acent to the interface. SP tests demonstrated strong dependence of the deformation and fracture behavior on the various coatings regimes. Coatings I and I1 showed higher microhardness and easier formation of brittle cracks in a wide temperature range, compared to coatings 111 and IV. The coating III had lower room temperature ductility and conversely higher elevated temperature ductility than the coating IV 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 ductity in the layered structure.
doi:10.2172/505288 fatcat:ldcvsmbvefbdndnzz5ep6hi4ae