Refractory high-entropy alloys(RHEAs)demonstrate exceptional high-temperature performance,extending their application potential beyond superalloys.Understanding the precise phase stability in RHEAs is crucial for desi...Refractory high-entropy alloys(RHEAs)demonstrate exceptional high-temperature performance,extending their application potential beyond superalloys.Understanding the precise phase stability in RHEAs is crucial for designing materials and microstructures with optimized properties.This study establishes a thermodynamic database for the Mo–Nb–Ta–W–Hf–Zr system within a third-generation(3rd-generation)thermodynamic framework,enabling the prediction of phase stabilities in different RHEAs.Initially,a third-generation thermodynamic model was proposed for solid and liquid phases in stable and metastable states,applied to Mo,Nb,Ta,W,Hf,and Zr elements to ensure lattice stability across the temperature range.Subsequently,9 sub-binary and 10 subternary systems within the Mo–Nb–Ta–W–Hf–Zr system were thermodynamically modeled under the 3rd-generation thermodynamic framework,demonstrating that the calculated results agree well with the measurements.By leveraging the optimized binary and ternary coefficients,a thermodynamic database for Mo–Nb–Ta–W–Hf–Zr was established applying the calculation of phase diagram approach.The reliability of this database was confirmed through equilibrium thermodynamic calculations as well as non-equilibrium solidification simulations in the Mo Nb Ta WZr alloys,exhibiting agreement with the experimental data.Ultimately,the database was utilized to predict phase stability in various RHEAs within the Mo–Nb–Ta–W–Hf–Zr system.The current predictions suggest that the precipitation temperatures of hexagonal close-packed_A3 and C15 Laves phases are relatively high,mostly above 1000 K,whereas that of the B2 phase is below 928 K.With an increase in the number of elements,the precipitation behavior in the alloys tends to become more complex,leading to the formation of multiple precipitated phases.展开更多
基金financially supported by the National Natural Science Foundation of China(No.52101012)the Natural Science Foundation of Hebei Province,China(No.E202302154)。
文摘Refractory high-entropy alloys(RHEAs)demonstrate exceptional high-temperature performance,extending their application potential beyond superalloys.Understanding the precise phase stability in RHEAs is crucial for designing materials and microstructures with optimized properties.This study establishes a thermodynamic database for the Mo–Nb–Ta–W–Hf–Zr system within a third-generation(3rd-generation)thermodynamic framework,enabling the prediction of phase stabilities in different RHEAs.Initially,a third-generation thermodynamic model was proposed for solid and liquid phases in stable and metastable states,applied to Mo,Nb,Ta,W,Hf,and Zr elements to ensure lattice stability across the temperature range.Subsequently,9 sub-binary and 10 subternary systems within the Mo–Nb–Ta–W–Hf–Zr system were thermodynamically modeled under the 3rd-generation thermodynamic framework,demonstrating that the calculated results agree well with the measurements.By leveraging the optimized binary and ternary coefficients,a thermodynamic database for Mo–Nb–Ta–W–Hf–Zr was established applying the calculation of phase diagram approach.The reliability of this database was confirmed through equilibrium thermodynamic calculations as well as non-equilibrium solidification simulations in the Mo Nb Ta WZr alloys,exhibiting agreement with the experimental data.Ultimately,the database was utilized to predict phase stability in various RHEAs within the Mo–Nb–Ta–W–Hf–Zr system.The current predictions suggest that the precipitation temperatures of hexagonal close-packed_A3 and C15 Laves phases are relatively high,mostly above 1000 K,whereas that of the B2 phase is below 928 K.With an increase in the number of elements,the precipitation behavior in the alloys tends to become more complex,leading to the formation of multiple precipitated phases.
