LAUSR

Abstract Thermodynamic criteria of lattice distortion energy (△Hel) and enthalpy of mixing (△Hmix) 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 (CoC[rNi)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.