|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Computational Materials Discovery and Optimization – From Bulk to Materials Interfaces and 2D Materials
||First-principles Statistical Mechanics as Applied to High Temperature Ni-superalloys
||John Goiri, Anton Van der Ven
|On-Site Speaker (Planned)
Mechanical strength, high melting temperature, and oxidation and creep resistance make nickel based superalloys an ideal candidate for high temperature industrial applications. First-principles DFT calculations combined with statistical mechanics enable not only a prediction of the stability of known phases, but also facilitate the discovery of previously unknown ordered phases. First-principles effective Hamiltonians combined with Monte Carlo simulations yield free energies that predict phase stability at elevated temperatures. Applied to the Ni-Al binary and Ni-Al-Cr ternary, we discover a family of previously unknown ordered phases that are stable at compositions where the alloy transitions from FCC to BCC. We explore dynamical instabilities at compositions where martensitic transformations are observed, and identify convenient strain order parameters to track instabilities along the Bain path. Ordering of vacancies and ternary alloying additions are investigated with the cluster expansion approach. The resulting free energy description enables the calculation of high temperature oxidation phase diagrams.
||Definite: None Selected