Phase separation and ordering process in Al-Li alloys studied by small-angle neutron scattering and neutron diffraction.

摘要

To study phase separation kinetics of Al-9.5at.%Li polycrystalline alloys in which precipitates have ordered Al(sub 3)Li ((delta)(prime)) structure, profile analysis of small-angle neutron scattering and superlattice reflections (100) and (110) were done. A small-angle scattering instrument and a triple-axis spectrometer in elastic mode were used in the measurements. Strong texture was observed in the reflections. Therefore, measurements were done using the crystal orientation where the intensity of the reflection was at the maximum. Profiles of small-angle scattering and superlattice reflections were almost identical at higher momentum transfer side. At lower momentum transfer side, small-angle scattering showed interference effects, but superlattice reflection did not show any sign of interference. Integrated intensities of superlattice reflections were obtained and compared with small-angle scattering intensity. The order parameter was not saturated in the (delta)(prime) precipitates at the early stage of the phase separation process.