Abstract
In order to investigate the solid solubility of B in Ni as a function of grain size, the high temperature internal friction of pure Ni and Ni–B alloys containing 0.0035, 0.0068 and 0.010 wt% B has been measured with particular attention to the grain boundary damping peaks. The electrical resistivity was also measured to determine the solubility. The results obtained are summarized as follows:
(1) The solubility of B in single crystal Ni is given by C(at%)=0.59exp(−H⁄RT), H=65.6 kJ/mol.
(2) The apparent solubility of B in polycrystalline Ni increases remarkably with decreasing grain size.
(3) On the Q−1−1⁄T curves of pure Ni, there are two peaks of grain boundary damping at about 470°C and about 670°C. By addition of 0.0035 wt% B, only one peak can be observed. The peak temperature of every Ni–B alloy used is about 550°C and its activation energy is about 330 kJ/mol.
