The effect of silicon, germanium, tin (X), and aluminum on the structure, physicochemical and mechanical properties of 8.5 at.% Al and 7.5 at.% B) quaternary alloys is studied by metallography, scanning electron microscopy (SEM), X-ray diffraction, differential thermal analysis (DTA), microhardness measurements, Vickers hardness measurements (from room temperature to 900°C), bending tests (room temperature), and compression tests (from room temperature to 700°C). The alloys are melted in an arc furnace from pure materials. Doping with p-elements (Al, Si, Ge, and Sn) does not change the specific titanium-boride eutectic structure in the two-phase (Ti) + TiB field. The doping additions hardly change the chemical composition of the eutectic and only decrease the boron content by 1-2 at.%. The Al, Si, Ge, and Sn (p-elements)
are not soluble in TiB titanium borides and completely concentrate in the metal matrix in two-phase (Ti) + TiB alloys. The temperature of incipient sharp softening is shown to be exclusively connected with the matrix composition. It is determined that p-elements increase the hardness and strength of titanium-boride eutectic alloys in the entire temperature range of interest and increase the temperature of incipient sharp softening from 500 to 600-650°C.
INTRODUCTIONTitanium monoboride (TiB) is a promising compound for reinforcement of titanium alloys and producing titanium-matrix composites. It is in thermodynamic equilibrium with the titanium-based phase characterized by low boron solubility. The boride and titanium phases have close thermal expansion coefficients and show favorable crystallographic coherency (the structure of the phases is shown in Table 1). Titanium boride is refractory and hard and has good wear resistance and high Young's modulus.Analysis of scientific publications of the last years shows that the number of papers focusing on titanium-matrix boride-reinforced composites increases. Test materials are mainly produced with powder metallurgy
