After heating the mixtures to 1063◦C, Ti2Cu disappeared and thephases of TiC, TiB2and Cu were identified in the final products with-out any intermediate phase, as shown in Fig. 3b. Thus, it is believedthe second exothermic peak in the DTA curve of 40 wt.% Cu–Ti–B4Cmixture was the formation of large amounts of TiC and TiB2parti-cles. When the mixtures were heated to 1200◦C, the compositionof reaction products did not change. When the temperature wasincreased much, more Cu–Ti liquid was formed and spread overthe reactants, and then C and B atoms continuously diffuse into the liquid and formed the Cu–Ti–B–C liquid. As a result, TiC and TiB2particles gradually precipitate out of the saturated liquid. With theconsumption of Ti in the liquid caused by the precipitation of TiCand TiB2, free Cu was displaced. The reaction was terminated afterTi atoms were depleted in the liquids. A typical back scatter imageof the reaction product heated to 1200◦C is shown in Fig. 4c.The melting temperature of the steel matrix is about 1500◦C inthis study, which significantly higher than the formation temper-ature (960◦C, as mentioned above) of the TiC and TiB2. When themolted steel was poured into the sand mold, the SHS reaction of theCu–Ti–B4C system was ignited by the heat released for the meltedsteel.