Cermet is an advanced class of material consisting of a hard ceramic phase along with a metallic binding phase with the combined advantages of both the ceramic and the metal phase. The superior properties of this class of materials are particularly useful in high-temperature, tribological, and machining applications. This review paper seeks to provide a comprehensive overview of the various cermet systems. More specifically, the most commonly used cermet systems based on tungsten carbide (WC), titanium carbide (TiC), titanium carbonitride (TiCN), and aluminum oxide (Al₂O₃) are discussed based on their development, properties, and applications. The effect of different metallic binders and their composition on the tribological and mechanical properties of these cermet systems is elaborated. The most common processing techniques for cermet systems, such as powder metallurgy (PM), reaction synthesis (RS), thermal spray (TS), cold spray (CS), and laser-based additive manufacturing techniques are discussed. The influence of the processing parameters in each case is evaluated. Finally, the applications and challenges of cermet systems are summarized.

Ultrasonic nanocrystal surface modification (UNSM) is a unique, mechanical, impact-based surface severe plastic deformation (S²PD) method. This newly developed technique finds diverse applications in the aerospace, automotive, nuclear, biomedical, and chemical industries. The severe plastic deformation (SPD) during UNSM can generate gradient nanostructured surface (GNS) layers with remarkable mechanical properties. This review paper elucidates the current state-of-the-art UNSM technique on a broad range of engineering materials. This review also summarizes the effect of UNSM on different mechanical properties, such as fatigue, wear, and corrosion resistance. Furthermore, the effect of USNM on microstructure development and grain refinement is discussed. Finally, this study explores the applications of the UNSM process.