Refractory high-entropy alloys(RHEAs)are emerging as new materials for high temperature structural applications because of their stable mechanical and thermal properties at temperatures higher than 2273 K.In this stud...Refractory high-entropy alloys(RHEAs)are emerging as new materials for high temperature structural applications because of their stable mechanical and thermal properties at temperatures higher than 2273 K.In this study,the mechanical properties of MoNbTaTiW RHEA are examined by applying calculations based on first-principles density functional theory(DFT)and using a large unit cell with 100 randomized atoms.The phase calculation of MoNbTaTiW with CALPHAD method shows the existence of a stable body-centered cubic structure at a high temperature and a hexagonal closely packed phase at a low temperature.The predicted phase,shear modulus,Young’s modulus,Poisson’s ratio,and hardness values are consistent with available experimental results.The linear thermal expansion coefficient,vibrational entropy,and vibrational heat capacity of MoNbTaTiW RHEA are investigated in accordance with Debye-Grüneisen theory.These results may provide a basis for future research related to the application of RHEAs.展开更多
基金the NSF EPSCoR CIMM project under the award#OIA-1541079 and DoD support under the W911NF1910005 contractComputational simulations were supported by the Louisiana Optical Network Infrastructure(LONI)with the supercomputer allocation loni_mat_bio12.
文摘Refractory high-entropy alloys(RHEAs)are emerging as new materials for high temperature structural applications because of their stable mechanical and thermal properties at temperatures higher than 2273 K.In this study,the mechanical properties of MoNbTaTiW RHEA are examined by applying calculations based on first-principles density functional theory(DFT)and using a large unit cell with 100 randomized atoms.The phase calculation of MoNbTaTiW with CALPHAD method shows the existence of a stable body-centered cubic structure at a high temperature and a hexagonal closely packed phase at a low temperature.The predicted phase,shear modulus,Young’s modulus,Poisson’s ratio,and hardness values are consistent with available experimental results.The linear thermal expansion coefficient,vibrational entropy,and vibrational heat capacity of MoNbTaTiW RHEA are investigated in accordance with Debye-Grüneisen theory.These results may provide a basis for future research related to the application of RHEAs.
