Developing CALPHAD-type models for Zr-C-O high-temperature ceramics considering the effects of short-range-ordering

在2022财年，密度泛函理论(DFT)的计算被用来进一步研究C-O-Zr系统，包括改进先前计算的团簇展开方法和产生特殊的准随机结构(SQS)来研究不同成分的无序相。针对这些结果评估晶格参数，并按计划在计算的合成空间中映射。结果在国际会议上公布：MS&T2022(亲自在美国匹兹堡)-邀请，ICAMMM(虚拟在印度昌迪加尔)-邀请主旨，和国际研讨会：Thermo-Calc(虚拟在瑞典斯德哥尔摩)研究网络研讨会-邀请，加州大学戴维斯分校(亲自在美国戴维斯)研究研讨会-邀请。拟议工作的目的是探索C-O-Zr系统以了解超高温陶瓷(UHTC)ZRC的氧化行为。近年来，以ZRC结构为基础的高熵UHTCs出现了一个令人振奋的新领域，即用多主成分的难熔过渡金属如Zr、Hf、Ti、Ta、Nb取代Zr。与ZRC等单一金属碳化物相比，这些高熵UHTC具有更好的抗氧化性。因此，除了探索C-O-Zr相图外，还对一些高熵UHTC的性质进行了探索。这项工作的成果已在ICACC2023会议(在美国代托纳海滩面对面)上公布，随后提交给ECERS 2023(将于2023年7月在法国里昂举行)的摘要被选为重点介绍。

In FY2022, density functional theory (DFT) calculations were performed to further examine the C-O-Zr system, including improving the cluster expansion method calculations calculated previously and generating special quasirandom structures (SQS) to examine disordered phases at different compositions. The lattice parameter was evaluated for these results and mapped as planned across the calculated composition space. Results were presented at international conferences: MS&T2022 (in-person in Pittsburgh, USA) - Invited, ICAMMM (virtually in Chandigarh, India) - Invited keynote, and international seminars: Thermo-Calc (virtually in Stockholm, Sweden) research webinar - Invited, UC Davis (in-person in Davis, USA) research seminar - Invited.The aim of the proposed work was to explore the C-O-Zr system to understand oxidation behaviour of the ultra-high temperature ceramic (UHTC) ZrC. In very recent years, an exciting new field has emerged of “high-entropy” UHTCs based on the ZrC structure, where Zr is replaced with multi-principal component refractory transition metals such as Zr, Hf, Ti, Ta, Nb. These high-entropy UHTCs have improved oxidation resistance compared to the single metal carbides such as ZrC. Therefore, in addition to exploring the C-O-Zr phase diagram, the properties of some high-entropy UHTCs have also been explored. Results from this work was presented at the ICACC2023 conference (in-person in Daytona Beach, USA), and following this an abstract submitted to ECerS 2023 (to take place in Lyon, France, in July 2023) has been selected as a highlight presentation.