Aditya Sundar1,Yong-Jie Hu2,Liang Qi1
University of Michigan1,Drexel University2
Aditya Sundar1,Yong-Jie Hu2,Liang Qi1
University of Michigan1,Drexel University2
Body-centered cubic (bcc) refractory alloys are of great interest for nucleation applications due to their remarkable strength at high temperatures. Optimizing the chemical compositions of these alloys to achieve a combination of high strength, high room-temperature ductility, and high resistance to performance degradation (such as oxidation and corrosion) remains challenging. With these electronic/atomistic descriptors and a simple bond-counting model, we developed regression models to accurately and efficiently predict the unstable stacking fault energy (γ<sub>usf</sub>) and surface energy (γ<sub>surf</sub>) for refractory multicomponent alloys. We performed first-principles calculations with the special quasi-random structure (SQS) method to predict γ<sub>usf</sub> and γ<sub>surf</sub> for > 100 individual binary, ternary, and quaternary bcc solid-solution alloys with constituent elements among Ti, Zr, Hf, V, Nb, Ta, Mo, W, Re, Ru, Cr, and Al. Then we developed surrogate models based on statistical regression to accurately and efficiently predict γ<sub>usf</sub> and γ<sub>surf</sub> for refractory multicomponent alloys in the 12-element compositional space. Building upon binary and ternary data, the surrogate models show outstanding predictive capability in the high-order multicomponent systems. The ratio between γ<sub>usf</sub> and γ<sub>surf</sub> can be used to populate a model of intrinsic ductility based on the Rice model of crack-tip deformation. Therefore, using the surrogate models, we performed a systematic screening of γ<sub>usf</sub>, γ<sub>surf</sub>, and their ratio over a large range of alloy compositions to search for alloy candidates that may have enhanced strength-ductility synergies. Search results were also validated by additional first-principles calculations and reported experimental results. Alloy compositions with the appropriate amount of Cr and Al could be good candidates to increase the corrosion resistance since it is possible to form compact passive oxide layers to prevent continuous oxidation and corrosion at high temperatures.