The effect of B and Ti-Al intermetallics additions on the microstructure and mechanical of hot B4C

In this work, we studied the microstructure and mechanical properties of hot-pressed B4C, B4C + 5 wt% TiAl, and B4C + B + 5 wt% TiAl. The X-ray diffraction and Raman spectroscopy results showed that the addition of Ti-Al alone did not led to Al doping in B4C , and it did not reduce the degree of amorphization of B4C generated under high shear stresses. In contrast, the co-addition of Ti-Al and B resulted in both B and Al solid solutions in the B4C and effectively mitigated the amorphization of B4C . Electron probe microanalysis (EPMA) and energy dispersive X-ray spectroscopy (EDS) analyses suggested that the co-addition of Ti-Al and B promoted the interdiffusion of lightweight elements such as B, C, Al, Mg, and Si at high temperatures, resulting in a dense body with uniformly distributed second phase. The transmission electron microscopy (TEM) observations of the B4C + B + 5 wt% TiAl sample showed that a nano-core-shell structure with aggregated dislocations in the shells which was generated at TiB2 grains due to the segregation and dissolution-precipitation between TiB2 and B-rich boron carbide. The short-range ordered substitution of B and the disordered doping of Al in B4C led to lattice distortion and expansion, resulting in the formation of high-density defects, including stacking faults and nano-twins, improving the mechanical properties for B4C . The B4C + B + 5 wt% TiAl sample exhibits a combination of fascinating properties, including low density (2.52 g/cm(3)), high Vickers hardness (35.53 +/- 0.83 GPa) and moderate fracture toughness (4.37 +/- 0.35 MPa m(1/2)).