Eutectic Ceramic Composites by Melt-Solidification

Abstract

While high-temperature ceramic composites consisting of carbides, borides, and nitrides, the so-called ultra-high-temperature ceramics (UHTCs), have been commonly produced through solid-state sintering, melt-solidification is an alternative method for their manufacture. As many UHTCs are binary or ternary eutectic systems, they can be melted and solidified at a relatively low temperature via a eutectic reaction. The microstructure of the eutectic composites is typically rod-like or lamellar, as determined by the volume fraction of the second phase. Directional solidification can help fabricate more sophisticated UHTCs with highly aligned textures. This review describes the fabrication of UHTCs through the eutectic reaction and explains their mechanical properties. The use of melt-solidification has been limited to small specimens; however, the recently developed laser technology can melt large-sized UHTCs, suggesting their potential for practical applications. An example of laser melt-solidification of a eutectic ceramic composite is demonstrated.

Determining Compositional Variation in Silicon–Metal Alloys by Parsing SEM/EDS Hyperspectral Images

“…This drove our interest in studying how metal-silicon ratios impact microstructure in binary and ternary Si-rich alloys. The design space for alloys that incorporate multiple metals is quite broad and selecting the appropriate compositions to result in dense microstructure is often aided by the construction of phase diagrams (Goto & Tu, 2019). The binary phase diagrams are available for all of the metal-metal and metal-silicon pairs investigated in this study (Smith, 1981(Smith, , 1983Smith et al, 1982;Venkatraman & Neumann, 1986Gokhale & Abbaschian, 1987;Schlesinger et al, 1993;Schlesinger, 1994;Okamoto, 2005;Ravi et al, 2012).…”