Abstract
Low frequency internal friction (f∼1 Hz) has been measured on titanium specimens containing 0.5–7 at% H or D over the temperature range from 10 to 650 K. A large internal friction peak appears as the dissolution or precipitation of hydrides occurs, being accompanied by self-twist of a wire specimen. The temperature of the peak is very different between heating and cooling runs, indicating a large hysteresis in precipitation and dissolution. The hysteresis and the twist behaviour are interpreted in terms of elastic and plastic accommodation of the misfit strain between the hydride and matrix. The magnitude of the hysteresis is discussed quantitatively, following Puls’s approach.
Below room temperature three relaxation peaks are observed. One located at the lowest temperature (P1) is identified as a dislocation relaxation peak, and the other two (P2 and P3) are considered to be related to hydride precipitates. The relaxation parameters of the peak P2 are dependent on different isotopes of hydrogen.
