A Study of Low Young's Modulus Ti–15Ta–15Nb Alloy Using TEM Analysis.

The microstructural characteristics and Young's modulus of the as-cast Ti–15Ta–15Nb alloy are reported in this study. On the basis of the examined XRD and TEM results, the microstructure of the current alloy is essentially a mixture (α + β+ α′ + α″ + ω + H) phase. The new H phase has not previously been identified as a known phase in the Ti–Ta–Nb alloy system. On the basis of examination of the Kikuchi maps, the new H phase belongs to a tetragonal structural class with lattice parameters of a = b = 0.328 nm and c = 0.343 nm, denoting an optimal presentation of the atomic arrangement. The relationships of orientation between these phases would be {0001}_α//{110}_β//{ 1 ¯ 2 1 ¯ 0}_ω//{10 1 ¯ }_H and (01 1 ¯ 0)_α//(1 1 ¯ 2)_β//( 1 ¯ 010)_ω//(121)_H. Moreover, the Young's modulus of the as-cast Ti–15Ta–15Nb alloy is approximately E = 80.2 ± 10.66 GPa. It is implied that the Young's modulus can be decreased by the mixing of phases, especially with the presence of the H phase. [ABSTRACT FROM AUTHOR]