- The pseudopotential approach is applied for a priori estimation of the efficiency of different additives to prevent fiber degradation in titanium-matrix/boron-fiber composites. The procedure is based on the pseudopotential calculations of excess energies of titanium-boron interstitial solid solution with and without additives to the matrix. Si, Ge, Al, V, Mo and Zr were tested as additives to the matrix. The limits of solubility of boron in titanium with and without additives are evaluated. The calculations are consistent with existing experimental data.