Investigation into some three-component solid solutions on the base of Nb3Al compound

The study of three-component solid solutions based on compound Nd3Al has been continued. The studies have been devoted to determining the effect of alloying elements Ti, Zr, Hf, V, Ta, Cr, Mo, W, Se on the lattice constant and Tsub(k) of compound Nb3Al. The chemical composition of the three-component alloys has been calculated so that Ti, Zr, Hf, V, Ta, Cr, Mo and W substituted niobium in compound Nb3Al, whereas Se substituted aluminium. The most elements added to Nb3Al form solid solutions of considerably great extension. The minimum solubility corresponds to chromium (4.5 atomic per cent) and zirconium (4 atomic per cent) which feature maximum value of the dimensional factor and maximum difference in electronegativity with refard to niobium (13%, 0.435 for Cr and 9.7%, 0.307 for Zr, respectively). According to the test results, the constant of the lattice of compound Nb3Al equals 5.1821+-0.0002 A. With the increase of the alloying element concentration in Nb3Al, the rate of change of the lattice constant (da/dc) directly depends on the dimensional factor. The maximum value is obtained when compound Nb3Al is alloyed with zirconium (da/dc=+66.10-4 A/atomic per cent) and the minimum value is achieved when the compound is alloyed with chromium (da/dc=-47x10-4 A/atomic per cent). In all considered cases, alloying of compound Nb3Al results in reduction of the critical temperature