About this Abstract |
Meeting |
MS&T21: Materials Science & Technology
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Symposium
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Integration between Modeling and Experiments for Crystalline Metals: From Atomistic to Macroscopic Scales III
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Presentation Title |
First-principles Study of the Effect of Al and Hf Impurities on Co3W Antiphase Boundary Energies |
Author(s) |
Chiraag Nataraj, Ruoshi Sun, Christopher Woodward, Axel van de Walle |
On-Site Speaker (Planned) |
Chiraag Nataraj |
Abstract Scope |
The effects of Al and Hf impurities on the (111) antiphase boundary (APB) energy of metastable FCC Co3W are investigated via ab initio calculations. Cluster expansions are used to predict the total energies of supercells containing non-dilute concentrations of impurities using Monte Carlo simulations at relevant temperatures. Two sets of compositions are explored for each system — constant ratio and sacrificial W. It is found that sacrificial W compositions are far more stable than constant ratio compositions and Hf increases the APB energy far more than Al. Additionally, at higher concentrations of Hf, Hf and W tend to segregate into alternating planes, unlike the Co-W-Al system, which explains the different impacts of the two impurities on the APB energy. Finally, the ratio of (111) to (100) APB energies is studied for sacrificial W compositions to understand cross slip behavior in both ternary systems. |