PHASE-SEPARATION IN TITANIUM HYDRIDES STUDIED BY SMALL-ANGLE NEUTRON-SCATTERING

Various phases of titanium hydrides with differing hydrogen and deuterium content are studied by small-angle neutron scattering. The low temperature metastable X phase produced by quenching under high pressure shows small, but pronounced scattering at liquid nitrogen temperature. At 140 K a very abrupt increase in the scattered intensity is detected, more than one order of magnitude for less than 30 s. The scattering from the room temperature (alpha+gamma) phase is analysed of the alpha-Ti precipitates in the gamma-TiH(D)1 matrix. A good representation is obtained in a random two-phase model, giving about 50 and 60 angstrom correlation lengths, independently of the deuterium or hydrogen content. For the delta phase, only the asymptotic behaviour of the scattering curves is observed in the scattering vector range covered in the experiments.