Mega-Gravity Experiment on In-Pb Alloy

A very strong gravity field can cause the sedimentation of atoms even in solids, and may be expected to create a nonequilibrium crystal-chemical state. A mega-gravity field experiment was performed on an In-Pb (80:20%mol) alloy, which forms a three-phase system, to study the sedimentation of atoms and the interaction with phase equilibria. This ultracentrifuge experiment was carried out using a turbine-motor type machine at a rotation rate of 205,000-221,000 rpm and a temperature of 150-160°C for 100 hours. The maximum acceleration was (0.87-1.02)×106 g at 18.6mm radius. A graded structure was observed on a cut surface of the ultracentrifuged sample by an electron-probe micro-analyzer. It was confirmed by X-ray diffraction that phase transformations occurred under the strong gravity field.