A NEW INTERNAL FRICTION PEAK ASSOCIATED WITH TRACE HYDROGEN IN Ti-6Al-4V ALLOY

Abstract
Internal friction measurements on commerical Ti-6Al-4V alloy in the range 100K to 350K at about 2 KHz frequencies revealed that there was not only a Snoek relaxation peak of hydrogen atoms in the β-phase at 116K, but also a new small relaxation peak at 289K caused by the small amount of hydrogen atoms in α-phase. The mechanism by which this new peak is produced is suggested. The activation energies for diffusion of hydrogen atoms in β-phase and α-phase were found to be 5.6 Kcal/mole and 11.1 Kcal/mole respectively. The frequency factors were 4.0 x 10¹⁴ and 2.3 x 10¹² S^-1 respectively. According to the height of the two peaks it is possible to evaluate the distrubition of hydrogen in two phases of Ti-6Al-4V alloy.