Effects of Alloying Elements on the Oxygen Snoek-type Relaxation in Ti-Nb Alloys

The effect of ternary alloying elements on the oxygen Snoek-type relaxation in the Ti-24Nb-2X-1.7O alloys (X = Al, Sn, Cr, Mn, Fe) was investigated. The dipole shape factor (delta lambda) of the Snoek-type relaxation was figured out for each ternary alloy based on the measured damping peak with the variable temperature. The value of delta lambda in the Ti-Nb-Al alloy was the highest among the present ternary alloys. It was found that delta lambda increased with the decreasing lattice constant as well as the decreasing valence electron number per atom (e/a) and came to a maximum value when the e/a value was around 4.24, which defined the beta phase boundary. Therefore, decreasing the lattice constants and the e/a value as largely as possible with alloying elements in the beta-Ti alloys is one of the feasible ways to increase delta lambda and to design the high damping Ti alloys.