Effect of active powder addition on the mechanical properties of TiCp/manganese steel matrix composites

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Abstract Different active powders were incorporated into TiC particle (TiCp) preforms of TiCp/manganese steel matrix composites to enhance the TiC/steel interfacial bonding. The effect of the active powders on bending strength and toughness of the composites was investgated. The composites were fabricated using a squeeze casting infiltration method, with a TiCp volume fraction of 50%. The active powders were mixed powders of Fe and tungsten carbide (WC), Ni and WC, and Ni and Si, respectively. Energy dispersive spectrometer (EDS) and transmission electron microscopy (TEM) were employed to analyze the interfacial microstructure of the composites. The results show that the addition of WCp results in the formation of a (W, Ti)C layer around TiCps, thereby strengthening the interfacial bonding. Conversely, the addition of Fe powder leads to the presence of significant glass-phase material at the interface, which is prone to cracking. Consequently, the composite with active Ni+WC exhibits notably higher bending strength (680.3 MPa) and impact toughness (7.7 J cm−2) compared to the composite with active Fe+WC (574.3 MPa and 2.6 J cm−2), with increases of 18.5% and 196.2%, respectively. Furthermore, the composite with active Ni+Si demonstrates the highest bending strength (886.7 MPa) and good toughness (4.3 J cm−2), which are 54.4% and 65.4% higher than those of the Fe+WC active composite, respectively, and its strength is 30.3% greater than that of the Ni+WC active composite. This improvement is attributed to enhanced wettability between TiCp and the matrix.