Phase transformations in a binary 10 at % Si-90 at % Al alloy at high pressures and temperatures

Differential barothermal analysis of the phase transformations in a 10 at % Si-90 at % Al alloy has been performed at temperatures up to 700°C in an argon atmosphere compressed to 100 MPa. A slight change of the eutectic melting/solidification temperature is found. The liquidus temperature of the alloy, which is determined upon melting and solidification, coincides with that determined at atmospheric pressure. At 551–554°C, an aluminum-based solid solution decomposes with the formation of silicon nanoprecipitates. The porosity of the alloy after barothermal analysis is almost unchanged. The lattice parameters of micron-sized silicon particles decrease, whereas those of nanoparticles increase relative to the tabulated parameters. The lattice parameters of aluminum subjected to solidification and cooling in a compressed argon medium decreases. The micorhardness of the aluminum matrix of the alloy corresponds to that of pure aluminum.