The site occupancy of H in a 20at%Mo alloy was investigated at room temperature, for H concentrations of 2.6, 4.2 or 8at%, by using a channelling method which involved the nuclear reaction, 1H(11B,a)aa. Contrary to previous results for lower Mo contents, a large fraction of the H atoms was found to be located in tetrahedral sites. Octahedral site occupancy was observed for the first time. The H distribution depended upon the H concentration. For concentrations of 2.6 or 4.2at%, some 20 to 30% of the H atoms were located at octahedral sites while, at a concentrations of 8at%, the fraction of octahedral-site occupancy dropped sharply to between 0 and 10%.

Change of Site Occupancy of Hydrogen in Nb on Alloying with Undersized Mo. E.Yagi: Journal of the Physical Society of Japan, 1998, 67[1], 340-4