TY - GEN A1 - Li, Longjun A1 - Wang, Li A1 - Liang, Zhida A1 - He, Junyang A1 - Qiu, Jingwen A1 - Pyczak, Florian A1 - Song, Min T1 - Effects of Ni and Cr on the high-temperature oxidation behavior and mechanisms of Co- and CoNi-base superalloys T2 - Materials and Design N2 - The high-temperature oxidation behaviors of Co- and CoNi-base alloys with different Ni and Cr additions were investigated by isothermal oxidation in air at 900 and 1000 °C. The structure, composition, and element distribution in the three layers within the oxide scales in different alloys have been explored in detail by electron microscopy, especially with regard to the fine oxide particles in the intermediate layer. Based on the microstructure and phase constitution of the oxide scales, the synergetic effects of alloying elements on the oxidation mechanisms and resistance have been elucidated in detail with the aid of CALPHAD calculation. Y1 - 2022 U6 - https://doi.org/10.1016/j.matdes.2022.111291 SN - 1873-4197 VL - 224 ER - TY - GEN A1 - Wang, Li A1 - Kong, Yi A1 - Oehring, Michael A1 - Song, Min A1 - Pyczak, Florian T1 - Atomic site occupancy of alloying elements and Laves phase stability in γ-γ′ Co-base superalloys T2 - Journal of Alloys and Compounds N2 - The atomic site occupancy of alloying elements in the ZrCo2 and HfCo2 based Laves phases formed in the Co-9Al-9W-2Zr and Co-9Al-9W-2Hf alloys was experimentally determined by the combined techniques of energy-dispersive X-ray spectroscopy mapping with atomic resolution and the atom location by channeling enhanced microanalysis (ALCHEMI) method. The results show that both Al and W occupy the Zr site in the C15 and the Hf site in the C36 crystal structure. The atomic locations of Al and W were further confirmed by comparing calculated inelastic cross-sections with experimental ALCHEMI results. Using the determined atomic site occupancies of alloying elements, special quasirandom structure solid solution models with 192 atoms were constructed and employed in first-principles calculations. It is found theoretically that the energy of formation of the C15 structure is always lower than that of the C36 structure at 0 K in both ZrCo2 and HfCo2 phases, no matter whether Al and W are incorporated or not. However, further ab initio molecular dynamics simulations suggest that lattice vibration at finite temperature contributes significantly to the phase stability, stabilizing the C36 structure compared to the C15 type for the (Hf, Al, W)Co2 phase at finite temperature, which fits well with the experimental findings. Y1 - 2022 U6 - https://doi.org/10.1016/j.jallcom.2022.164261 SN - 1873-4669 SN - 0925-8388 VL - 906 ER - TY - GEN A1 - Wang, Li A1 - Liang, Xiaopeng A1 - Liu, Bin A1 - Oehring, Michael A1 - Paul, Jonathan David Heaton A1 - Liu, Jie A1 - Song, Min A1 - Pyczak, Florian A1 - Liu, Yong T1 - Stacking fault formation in perovskite Ti3AlC carbides in a TiAl based alloy during creep at 800°C T2 - Scripta Materialia Y1 - 2023 U6 - https://doi.org/10.1016/j.scriptamat.2022.115034 SN - 1872-8456 SN - 1359-6462 VL - Vol. 222 ER -