Abstract

Exploring the wetting behavior of active filler alloys on high-entropy ceramic is critical to clarifying the solid/liquid interface reaction mechanism and guiding the preparation of high-performance composites. The wetting and spreading behaviors of the molten Ti-Ni-xNb filler alloys, both without and with different Nb concentrations, on (HfTaZrNbTi)C high-entropy carbide (HEC) ceramic were investigated at 1330 °C under a vacuum atmosphere using a sessile drop method. The wetting process of the Ti-Ni-xNb filler alloys was characterized by four distinct stages: (i) adhesion stage, (ii) rapid decreasing stage, (iii) sluggish spreading stage, and (iv) final equilibrium stage. The Ti-Ni-xNb filler alloys all exhibited good wettability on the HEC ceramic, with the final contact angle remaining around 47-48°. The interfacial structure was identified as a sequence of HEC/Ti-based HEC’ diffusion layer/TiCx reaction layer/Ti2Ni layer/alloy droplet in all wetting systems. Notably, the introduced Nb element participated in the interfacial reactions between HEC and the filler alloy, modifying the morphology of the solidified droplet and accelerating the rapidly decreasing stage of the alloys on the ceramic. Nb atoms replaced some of the Ti atoms in the TiCx reaction layer, which restrained the atomic diffusion, leading to the formation of thinner reaction layers. The spreading kinetics were initially governed by interfacial reactions and later by the diffusion of Ti and Ni into the ceramic substrate, exhibiting a transition from reaction-controlled to diffusion-controlled spreading.

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