Partial or total substitution of Cobalt by Nickel and of Hf by Ta or Zr in cast polycrystalline chromium–rich superalloys

P. Berthod, D.A. Kane, S. Tlili
Institut Jean Lamour (University of Lorraine),

Keywords: cast superalloys, Co by Ni substitution, Hf by Ta substitution, Hf by Zr substitution, microstructures, high temperature properties


The purpose of the present paper is to share some results about several new superalloys with promising properties of chemical resistance (against oxidation) and of mechanical strength (against creep deformation): · All resulting from the total substitution of Co by Ni as base element from reference alloys · Some of them resulting from the substitution, in resistant Ni–based superalloys reinforced by HfC, of a part of Hf by Ta, without loss of the high temperature stability of the MC–carbides (problem earlier met for TaC in (Ni,Cr)–based alloys) · The other alloys resulting to the total replacement of the expensive and rare Hf element, by Zr. As shown in our recent studies, these modified superalloys present potential very interesting properties beyond 1100°C allowing them competing the (Co,Cr)–based alloys strengthened by HfC for service at elevated temperature. Their microstructural, oxidation and mechanical properties will be presented.