Using a furnace owned by the European Space Agency, astronauts heated and cooled three samples of aluminum and indium of different compositions at temperatures over 1,000 C. Preliminary experiments done in low gravity had shown that fibers of indium formed inside a matrix of aluminum. Some data were lost, and several samples formed bubbles. The researchers are still analyzing the unexpected imperfections. B ased on earlier results, Andrews chose an aluminum nitride container for the 1996 experiments in order to minimize the wetting behavior. Some scientists, however, have gotten rid of containers altogether.
Scientists can then heat and cool the samples and measure their physical properties.
The sample is completely spherical. Spherical samples can provide more accurate measurements. The containerless technique enables scientists to study crystallization over a greater temperature range than is possible on Earth. To study the crystallization, the scientists melt the sample, then cool it carefully below its freezing point. The scratches serve as nucleation sites, or starting points for the crystal formation.