Microstructure evolution and mechanical properties of (CoCrNi)90(AlTiZr)5(CuFeMo)5 multicomponent alloy: A pathway through multicomponent alloys toward new superalloys

• Published in: Journal of alloys and compounds 2021-04, Vol.860, p.158412, Article 158412
• Main Authors: Pouraliakbar, Hesam, Shim, Sang Hun, Kim, Yong Keun, Rizi, Mohsen Saboktakin, Noh, Hyeonbae, Hong, Sun Ig
• Format: Article
• Language: English
• Subjects: Alloy design; Alloy development; Alloys; Aluminum; Chromium; Compression tests; Copper; Deformation mechanisms; Dendritic structure; Enthalpy; Face centered cubic lattice; Intermetallic phases; Laves-phase; Mechanical properties; Microstructure; Morphology; Multicomponent alloy (MCA); Multiphase microstructure; Nickel; Phase stability; Solid phases; Strain rate; Structural stability; Superalloys; Thermodynamic criteria; Zirconium
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.158412

Thermodynamic criteria of lattice distortion energy (ΔHel) and enthalpy of mixing (ΔHmix) were considered to design and estimate the initial phase formation and stability in (CoCrNi)100−x−y(AlTiZr)x(CuFeMo)y multicomponent alloy (MCA) system. This study aimed to chase a new alloy design pathway to develop superalloys by benefitting from the concept of multiphase MCAs. The non-equilibrium cast microstructure (CoCrNi)100−x−y(AlTiZr)x(CuFeMo)y displayed a metastable dendritic structure consisting of primary Co-Cr-Ni-rich FCC dendrites and an interdendritic eutectic mixture, comprising supersaturated cubic Laves-phase and FCC phase. The composition of the AB2-structure Laves-phase was identified as (Zr, Cr, Cu, Al, Ti)(Ni, Co)2. Following the short-term annealing, a tenuous network of Zr-rich phase with a cubic structure was formed by the decomposition of the Laves-phase structure. Phase fraction along with the morphology of the intermetallic phase was altered by treatment and eventually semi-circular islands emerged. Results of tensile and compression tests at different strain rates exhibited the detrimental effect of structural instability and dependency of rate-sensitivity to alloy microstructure. Strain-rate increment enhanced the contribution of ductile failure with slip-band indications; however, this was accompanied by activation of further deformation mechanisms and subsequent formability improvement at a higher rate. •Multicomponent alloys’ concept was applied for the production of new high-temperature alloys.•Alloying system of (CoCrNi)100−x−y(AlTiZr)x(CuFeMo)y was systematically studied.•Cast alloy contained a metastable dendritic structure with typical hypoeutectic morphology.•Intermetallic Laves-phase of AB2-structure was identified as (Zr, Cr, Cu, Al, Ti)(Ni, Co)2.•The supersaturated Laves-phase decomposed and Zr-rich phase was formed by short-term annealing.