YOUNGS MODULUS AND INTERNAL-FRICTION OF YTTRIUM

A detailed study of the temperature dependence of Young's modulus E(T) and internal friction Q(-1)(T) has been made for various purity singl e crystals and polycrystalline samples of yttrium. Measurements have b een carried out in the temperature range 4.2 - 400 K at frequencies f similar to 1 kHz. It was found that E(bp) = 134 GPa and E(c) = 51 GPa at T = 4.2 K in the basal plane and along the c-axis, respectively. It was established that the E(T) curves for single crystals have a Debye -like shape in the temperature interval 4.2 - 320 K (the Debye tempera ture Theta(D) = 135 K and Theta(D) = 98 K in the case of basal plane a nd the c-axis, respectively. Q(-1)(T) at a temperature near 400 K disp lays maxima connected with relaxation processes of defects and disloca tions in the samples.