Liquid metal assistant self-propagating high-temperature synthesis of S-containing high-entropy MAX-phase materials

• Published in: Journal of materials science & technology 2025-02, Vol.209, p.1-8
• Main Authors: Bai, Donglong, Wang, Qiang, Deng, Bin, Li, Yang, Huang, Ao, Cheng, Zitong, Zhao, Yun, Li, Jing, Yao, Wei, Xu, Jianguang
• Format: Article
• Language: English
• Subjects: High-entropy; Liquid metal; LMA-SHS; S-containing MAX phases
• ISSN: 1005-0302
• DOI: 10.1016/j.jmst.2024.05.006

•A novel process named as liquid metal assistant self-propagating high-temperature synthesis (LMA-SHS) has been developed, which shows very short reaction time, low energy consumption, high yield, and low cost.•High-purity S-containing high-entropy MAX-phase materials have been successfully synthesized via LMA-SHS.•Liquid metal (Sn or In) acts as a binder among transition metal atoms by generating negative mixing enthalpy, and facilitates mass and heat transfer during the LMA-SHS process. Due to their high-entropy effects, the high-entropy (HE) MAX-phase materials improve the comprehensive performance of MAX phases, opening up more possibilities for practical engineering applications. However, it is still challenging to obtain S-containing high-entropy MAX phases because of the high volatilization behavior of sulfur, suffering from issues such as high reaction temperature and long reaction time of traditional synthesis methods. This paper proposes a novel process named as liquid metal assistant self-propagating high-temperature synthesis (LMA-SHS) for efficient synthesis of high-purity S-containing high-entropy MAX-phase materials. Low-melting-point metal (Sn or In) has been introduced into the raw mixture and melted into a liquid phase during the early stage of the SHS reaction. By serving as a “binder” between transition metal atoms of the M-site due to the negative mixing enthalpy, this liquid phase can accelerate mass and heat transfer during the SHS process, ensuring a uniform solid solution of each element and realizing the synthesis of high-purity (TiNbVZr)2SC in an extremely short time. The synthesis method for high-entropy MAX-phase materials developed in this study, i.e., LMA-SHS, showing very short reaction time, low energy consumption, high yield, and low cost, has the promise to be a general energy- and resource-efficient route towards high-purity HE materials. Two Synthesis Methods (SHS, LMA-SHS) and XRD patterns of S-containing high-entropy MAX-phase materials. [Display omitted]