Rapid liquid phase-assisted ultrahigh-temperature sintering of high-entropy ceramic composites

Hua Xie; Mingde Qin; Min Hong; Jiancun Rao; Miao Guo; Jian Luo; Liangbing Hu

doi:10.1126/sciadv.abn8241

Rapid liquid phase-assisted ultrahigh-temperature sintering of high-entropy ceramic composites

Sci Adv. 2022 Jul 8;8(27):eabn8241. doi: 10.1126/sciadv.abn8241. Epub 2022 Jul 6.

Authors

Hua Xie^{1

2}, Mingde Qin³, Min Hong^{1

2}, Jiancun Rao⁴, Miao Guo^{1

2}, Jian Luo³, Liangbing Hu^{1

2}

Affiliations

¹ Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742, USA.
² Center for Materials Innovations, University of Maryland, College Park, MD 20742, USA.
³ Department of NanoEngineering, University of California San Diego, La Jolla, CA 92093, USA.
⁴ Advanced Imaging and Microscopy Laboratory of Maryland NanoCenter, University of Maryland, College Park, MD 20742, USA.

Abstract

High-entropy ceramics and their composites display high mechanical strength and attractive high-temperature stabilities. However, properties like strong covalent bond character and low self-diffusion coefficients make them difficult to get sintered, limiting their mass popularity. Here, we present a rapid liquid phase-assisted ultrahigh-temperature sintering strategy and use high-entropy metal diboride/boron carbide composite as a proof of concept. We use a carbon-based heater to fast-heat the composite to around 3000 K, and a small fraction of eutectic liquid was formed at the interface between high-entropy metal diborides and boron carbide. A crystalline dodecaboride intergranular phase was generated upon cooling to ameliorate the adhesion between the components. The as-sintered composite presents a high hardness of 36.4 GPa at a load of 0.49 N and 24.4 GPa at a load of 9.8 N. This liquid phase-assisted rapid ultrahigh-temperature strategy can be widely applicable for other ultrahigh-temperature ceramics as well.