Creep of single-crystals of nickel-base γ-alloy at temperatures between 1150 °C and 1288 °C
Artikel i vetenskaplig tidskrift, 2021

A γ-analogue of the superalloy CMSX-4 that does not contain the strengthening γ′-phase and only consists of the γ-solid solution of nickel has been designed, solidified as single-crystals of different orientations, and tested under creep conditions in the temperature range between 1150 and 1288 °C. The tests have revealed a very high creep anisotropy of this alloy, as was previously found for CMSX-4 at supersolvus temperature of 1288 °C. This creep anisotropy could be explained by the dominance of 011111 octahedral slip. Furthermore, the analysis of the creep data has yielded a high value of the creep activation energy, Qc≈442 kJ/mol, which correlates with the high activation energy of Re diffusion in Ni. This supports the hypothesis that dislocation motion in the γ-matrix of Re-containing superalloys is controlled by the diffusion of the Re atoms segregating at the dislocation core. The Norton stress exponent n is close to 5, which is a typical value for pure metals and their alloys. The absence of γ′-reprecipitation after high-temperature creep tests facilitates microstructural investigations. It has been shown by EBSD that creep deformation results in an increasing misorientation of the existing low angle boundaries. In addition, according to TEM, new low angle boundaries appear due to reactions of the a/2011 mobile dislocations and knitting of new networks.

Electron microscopy

Nickel alloys

Single-crystals

Creep

Deformation mechanisms

Författare

Alexander Epishin

Technische Universität Berlin

B. Fedelich

Bundesanstalt für Materialforschung und -prüfung (BAM)

Bernard Viguier

Université de Toulouse

S. Schriever

Bundesanstalt für Materialforschung und -prüfung (BAM)

I. L. Svetlov

Russian Scientific Research Institute of Aviation Materials

N. V. Petrushin

Russian Scientific Research Institute of Aviation Materials

Romain Saillard

Université de Toulouse

A. Proietti

Université de Toulouse

D. Poquillon

Université de Toulouse

Anton Chyrkin

Chalmers, Kemi och kemiteknik, Energi och material, Oorganisk miljökemi

Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing

0921-5093 (ISSN)

Vol. 825 141880

Ämneskategorier

Annan kemiteknik

Annan materialteknik

Metallurgi och metalliska material

DOI

10.1016/j.msea.2021.141880

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Senast uppdaterat

2021-08-26