Wetting and interfacial phenomena in Ni–HfB2 systems

✍ Scribed by A. Passerone; M.L. Muolo; F. Valenza; F. Monteverde; N. Sobczak

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 643 KB
• Volume: 57
• Category: Article
• ISSN: 1359-6454
• DOI: 10.1016/j.actamat.2008.09.016

✦ Synopsis

The wettability and reactivity between polycrystalline hot-pressed HfB 2 and liquid Ni, Ni-Ti and Ni-B alloys have been investigated by the sessile drop method up to 1520 °C. Independently of the sintering aids (B 4 C, HfSi 2 ), high-temperature interactions led to the formation of a bimodal interface profile, due to the competition between the strong dissolution of HfB 2 in the liquid phase and drop spreading along the substrate surface. Ni demonstrates good wetting with the HfB 2 substrates (h = 20°). Compared to Ni, high Ti-containing alloys reveal much faster wettability kinetics with a final contact angle below 10°, accompanied by the formation of an interfacial Ti-rich reaction product. The eutectic NiB alloy shows complete wetting and fast spreading on HfB 2 and minor dissolution of the ceramic into the liquid, a clear indication that higher B contents could optimize the interfacial structure. These results are of practical interest for liquid-assisted composite synthesis and joining of HfB 2 -based ceramics.