Effects of local relaxation on lattice parameter and elastic properties of Ni-W alloys at high temperature: A first-principles study

Temperature-dependent properties are very useful in modeling the behavior of materials servicing at high temperature such as nickel-based superalloys. Besides, for predicting the mechanical properties of such alloys, experimental data at high temperature are very important, but scarce. For Ni-W alloys, both experimental and computational data are very rare. In this work, first-principles calculations are combined with a quasi-harmonic Debye model to evaluate the Helmholtz free energy of paramagnetic Ni-W binary solid solutions as a function of temperature, volume, and W content. Local relaxation around W atoms, which has often been ignored in electronic structure calculations for alloys, is considered in this work using supercell models. The effect of W on elastic properties has been analyzed, to evaluate the contributions due to local relaxation around W atoms. The calculated trends of bulk modulus and stiffness constants C11 and C12 to increase with W concentration are in good agreement with experimental measurements.

TEKNIK OCH TEKNOLOGIER Materialteknik hsv//swe
ENGINEERING AND TECHNOLOGY Materials Engineering hsv//eng
Ni-W solid solutions; elastic properties; lattice misfit; local relaxation; first principles calculations; high temperature.
Teknisk materialvetenskap
Materials Science and Engineering

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