Experimental technique for studying high-temperature phases in reactive molten metal based systems

Containerless microgravity experiments are designed to be conducted onboard of a NASA KC-135 aircraft flying parabolic trajectories. Equilibria in molten metal-gas systems will be studied using samples prepared as pellets of premixed solid components, e.g., mixtures of ZrO ₂, ZrN, and Zr powders. In an experiment, a small spherical specimen (1-2 mm diameter) will be acoustically levitated inside an argon-filled chamber at one atm. The sample will be heated and melted by a CO ₂ laser. The molten specimen will be equilibrated at high temperature and rapidly quenched between two metal plates. The solidified sample will be recovered for further phase analysis in a terrestrial laboratory. A uniaxial apparatus suitable for acoustic levitation, laser heating, and splat quenching of small samples has been developed and equipped with computer-based controller and optical diagnostics. The experimental setup has been characterized under normal gravity conditions. The most suitable operating parameters of the levitator have been determined by direct observation of levitated samples, as opposed to more traditional pressure mapping of the acoustic field. The size range of samples that can be reliably heated and quenched in this setup has been determined to be on the order of 1-3 mm in diameter.