3. Results and discussion
3.1. SHS reaction behavior of Cu–Ti–B4C system
The curve of temperature vs. ignition delay time for theCu–Ti–B4C system with 40 wt.% Cu during SHS reaction is shownin Fig. 2a. It is found that the combustion temperature (Tc) wasapproximately 2179◦C. The ignition delay time is also called igni-tion time which is the time interval from the start of heating tothe initiation of the self-propagating reaction. During this time, theexothermic reactions occurred and the combustion wave propa-gated. The short or long ignition time represents the reaction iseasy to occur or not, respectively. According to this study of Yanget al. [25], the solidification time of the austenite manganese steelmelt was estimated to be 62.7 s. It can be seen from Fig. 2a thatthe SHS reaction in the 40 wt.% Cu–Ti–B4C system was ignited after being afterbeing heated for 15.4 s, which was much shorter than the solidifica-tion time of the steel melt. During the solidification process of themelted steel, it has sufficient time to ignite SHS reaction of 40 wt.%Cu–Ti–B4C system, leading to the formation of unit materials.Fig. 2b shows the XRD results of the SHS products in the 40 wt.%Cu–Ti–B4C system. It can be seen that the products consisted ofTiC, TiB2and Cu without any intermediate phases, indicating thatthe reaction was complete. While, the pure TiC and TiB2ceramicparticles were formed during the SHS reaction. Therefore, it can beconfirmed that Cu content and particle size of the reactant mix-tures are proper parameters considered for fabricating the unitmaterials. Fig. 2c shows the microstructures of the SHS reactionproducts in the 40 wt.% Cu–Ti–B4C system, where the elongated orrectangular particles were TiB2, while the nearly spherical particleswere TiC. The TiC and TiB2ceramic particles were widely used asthe reinforcements in metal matrix composites due to its excellentproperties, such as high hardness, low density, high melting tem-perature, high modulus, high wear and corrosion resistances, andgood wettability and stability in metal melt [26]. Since the TiC andTiB2ceramic particles were widely used as the reinforcements inmetal matrix composites as aforementioned, the austenite man-ganese steel matrix reinforced with TiC and TiB2ceramic particlesproduced by SHS reaction of Cu–Ti–B4C system supposed to haveexhibited excellent mechanical properties in this study