Alloying-element dependence of structural, elastic and electronic properties of nickel-based superalloys: Influence of γ’ volume fraction

• Published in: Journal of alloys and compounds Vol. 838; p. 155141
• Main Authors: Lin, Yuan-Cheng, Wang, Chong-Yu
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.10.2020; Elsevier BV
• Subjects: Alloy development; Alloying additive; Alloying effects; Alloying elements; Bonding strength; Bulk modulus; Chromium; Density of states; Dependence; Dopants; Ductile-brittle transition; Elastic anisotropy; Elastic properties; Electronic properties; First principles; Mechanical properties; Modulus of elasticity; Molybdenum; Multilayers; Nickel; Nickel aluminides; Nickel base alloys; Nickel-based superalloys; Room temperature; Shear modulus; Superalloys; Tungsten; γ’ volume fraction; Electronic properties; First principles; γ’ volume fraction; Elastic properties; Nickel-based superalloys
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.155141

First-principles calculations are carried out to investigate the structural, elastic, and electronic properties of nickel-based model superalloys. The effects of alloying element X (where X = Hf, Ta, Mo, W, Cr, Re, Ru, or Co) on the mechanical characteristics of Ni/Ni3Al ternary multilayer structures are obtained and discussed. The γ’-volume-fraction dependence of mechanical performance is studied in detail for the first time and the calculated elastic parameters are in good agreement with experimental results at room temperature. The influence of alloying elements on bulk modulus is almost independent of γ’ volume fraction. While the effects of alloying elements on shear modulus, Young’s modulus, the ductile and brittle behavior, some particular orientation-dependent elastic moduli and Zener anisotropy factor are closely related to γ’ volume fraction. Alloying additions increase the Young’s and shear moduli, reduce the ductility and lower the anisotropy performance, but the degree of influence on these properties varies with γ’ volume fraction. Among the three γ’ volume fractions investigated in this work, nickel-based ternary model superalloys with 60% γ’ volume fraction have significant improvement in Young’s and shear moduli and thus possess the best comprehensive elastic performance. Furthermore, covalent-like bonding between alloying dopants and host atoms and strong X d- Ni d hybridization account for the superior elastic properties of superalloys with alloying additions. Alloying dopants and Ni atoms from the interface and two phases share a DOS peak just below the Fermi level, and this additional d-d hybridization leads to the exceptional mechanical performance of superalloys with 60% γ’ volume fraction. •Detailed research into alloying effects on elastic and electronic properties of Nickel-based model ternary superalloys are introduced.•The γ’-volume-fraction dependence of elastic properties of nickel-based super-alloys from theoretical calculations is investigated for the first time.•Nickel-based model ternary superalloys with 60% γ’ volume fraction (γ’-VF)have greater improvements of shear modulus and Young’s modulus than those with 50% γ’-VF and 70% γ’-VF.•An additional d-d hybridization has only been discovered for nickel-based two-phase ternary model alloys with 60% γ’ volume fraction.