Abstract
The influence of the interstitial elements H, B, C, N and O on the bulk modulus and the theoretical strength of α-Ti was investigated using the discrete variational method under the local density approximation from first principles. The electronic structure and the total and binding energies were first evaluated with and without lattice relaxation and then used to assess the theoretical values of the bulk modulus and the theoretical strength under hydrostatic tension. It was shown that the binding energy was increased when H was in a solution of α-Ti but reduced when B, C, N or O was in solution. The bulk modulus and the theoretical strength were increased by C, O and N but reduced by H and B. A charge-density analysis showed that the bonds between Ti atoms were enhanced by the interstitial elements N, C and O but weakened, to some extent, by the incorporation of H.