  Elastic properties of Ti based \beta-alloy were studied by the method of the
model structure first principle calculations. Concentrational dependence of
Young modulus for the binary \beta-alloy Ti-Nb was discovered. It is shown that
peculiarities visible at 15-18% concentrations can be related to the different
Nb atoms distribution. Detailed comparison of the calculation results with the
measurement results was done. Young modulus for the set of the ordered
structures with different Nb atoms location, which simulate triple \beta-alloys
Ti-29.7%Zr-18.5%Nb and Ti-51.8%Zr-18.5%Nb have been calculated. The results of
these calculations allowed us to suggest the concentration region for
single-phase ternary \beta-phase alloys possessing low values of Young's
modulus.
