To understand the dynamics of coarsening, a process that occurs in nearly any two-phase mixture found in nature.
Coarsening affects the properties of the many materials that are composed of more than one phase.
Heat off-eutectic alloys of Pb-Sn in a compact furnace to a temperature just above the eutectic melting point (~183°C) so that a solid-liquid mixture is achieved. Hold temperature for a predetermined time and rapidly solidify the mixture with a liquid water quench. Place samples in a -20°C freezer to maintain microstructure while in orbit. Perform metallographic analysis on ground.
|CSLM-1 Solid-Sn particles in a liquid Pb-SN alloy. The size of the particles increases with coarsening time t. In many materials, such as Ni-based superalloys used in jet turbine blades, this increase in size has a dramatic effect on the properties of the alloy.
Assess the validity of a theory with which nearly all multiphase materials are designed.
Result: A more rational design of materials from first principles, reduced development cost for the production of new materials and better materials properties.
CSLM-1 sample from MSL-1 mission
Ground Based Sample
|Ground-based coarsening experiments are negatively affected by gravity (buoyancy and convection). The microgravity environment of the International Space Station (ISS) is ideal for negating these material transport modes, leaving diffusion as the only form of material transport.
Coarsening in Solid-Liquid Mixtures (CSLM-2)
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