Internal friction of R-phase and B19′ martensite in equiatomic TiNi shape memory alloy under isothermal conditions

The intrinsic internal friction IF I of R-phase and B19′ martensite are composed of static internal friction IF S and dynamic internal friction IF D . The tan δ values of I F S R and I F S B 1 9 ′ are both proportional to σ 0 / υ 1/2 and are related to the stress-assisted motions of twin boundaries. The tan δ values of I F S R are higher than those of I F S B 1 9 ′ is owing to the softer storage modulus E 0 in R-phase. The tan δ values of I F D B 1 9 ′ are linearly proportional to T ˙ / υ 1 / 2 . The occurrence of relaxation peak at ≈−60 °C is found to come from the I F S B 1 9 ′ , instead of the I F D B 1 9 ′ .