Stability and Physical Properties of the L1(2)-gamma ' Phase in the CoNiAlTi-System

Pyczak F, Liang Z, Neumeier S, Rao Z (2023)

Publication Type: Journal article

Publication year: 2023

Journal

Metallurgical and Materials Transactions A-Physical Metallurgy and Materials Science ASM International

DOI: 10.1007/s11661-022-06949-y

Abstract

There is a current interest in Co-based superalloys hardened by a L1(2)-gamma ' phase because Co has a higher melting point than Ni and is more resistant against sulfidation attack. However, the Co-Al-W system many of those gamma ' hardened Co-based superalloys are based on, has a number of drawbacks. The gamma ' phase Co-3(Al,W) is not stable at high temperature, the density of the alloys is very high and the oxidation resistance is insufficient. Due to this, there is an ongoing interest to develop gamma '-hardened Co-based superalloys based on other systems. Here, first principles calculations are presented to investigate the properties of the gamma ' L1(2)-(Co-0.5,Ni-0.5)(3)(Al-0.5,Ti-0.5) phase and related L1(2) structures. (Co-0.5,Ni-0.5)(3)(Al-0.5,Ti-0.5) exhibits a lower energy of formation than Co3Ti and Co-3(Al-0.5,W-0.5). Nevertheless, Ni-3(Al-0.5,Ti-0.5) has an even lower energy of formation which is further lowered if Ti is enriched on the second sublattice. This finding is supported by analyzing the electronic densities of states. Ni-3(Al-0.5,Ti-0.5) and especially Ni-3(Al-0.25,Ti-0.75) exhibit Fermi levels close to the gap between binding and antibinding states, which is an indicator for stability. In addition to the stability of the gamma '-phase in dependence on Ni and Ti content, also the elastic properties were calculated. Ni-3(Al-0.25,Ti-0.75) is less elastic anisotropic and has higher Young's and shear modulus compared to Ni-3(Al-0.5,Ti-0.5) and (Co-0.5,Ni-0.5)(3)(Al-0.5,Ti-0.5).

Authors with CRIS profile

Steffen Neumeier Lehrstuhl für Werkstoffwissenschaften (Allgemeine Werkstoffeigenschaften)

Involved external institutions

Helmholtz-Zentrum Geesthacht Zentrum für Material- und Küstenforschung GmbH (HZG) DE Germany (DE) Max-Planck-Institut für Eisenforschung GmbH (MPIE) / Max Planck Institute for Iron Research DE Germany (DE)

How to cite

APA:

Pyczak, F., Liang, Z., Neumeier, S., & Rao, Z. (2023). Stability and Physical Properties of the L1(2)-gamma ' Phase in the CoNiAlTi-System. Metallurgical and Materials Transactions A-Physical Metallurgy and Materials Science. https://dx.doi.org/10.1007/s11661-022-06949-y

MLA:

Pyczak, F., et al. "Stability and Physical Properties of the L1(2)-gamma ' Phase in the CoNiAlTi-System." Metallurgical and Materials Transactions A-Physical Metallurgy and Materials Science (2023).

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