TiB₂-particle-reinforced high modulus steel (HMS) has been developed for designing high-performance automobile engine parts. Thermodynamic assessments of the Fe-X-Ti-B system revealed the direct equilibrium between TiB₂ and C-free iron-based matrices, and strongly supported the most effective contribution of TiB₂ particles to improving the isotropic Young's modulus. The stable region for the optimum phase combination of (a + TiB₂) or (g + a + TiB₂) has been determined with the effect of impurities inevitably mixed in practical P/M process.

The P/M process of HMS employed the In-situ synthesis reaction between ferro-Ti and ferro-B powders resulting in submicron-size TiB₂ particles.

Due to the alloy design with the above thermodynamic aspect, the relationship between particles fraction and Young's modulus of the HMS was in good agreement with the theoretically predicted value. And it demonstrates the achievement of high modulus surpassing even those of conventional hard steels including a high fraction of carbide particles.

The main raw powder for the HMS matrix has currently been a commercial low-alloyed steel powder considering its wide availability and low cost. Depending on the application, the high strength HMS is prepared by blending Cu powder that enhances the matrix by precipitation hardening. This article introduces the HMS with respect to the on-going development of tailored material as well as the concepts, alloy design, and microstructure/properties.