Effect of Hydrogen on the Structure and Properties of Eutectic Silumin with 15% Silicon

The effect of melt hydrogen treatment on structure, morphology, and on physical and mechanical properties of hypereutectic alloy Al - 15% Si in cast and deformed conditions is studied. A melt is treated with hydrogen by different methods, i.e., with wet asbestos, in a steam atmosphere, and flushing with hydrogen prepared by alkali decomposition with aluminum. Ingots are deformed plastically by open forging and rolling. Alloy microstructure is studied by metallographic, electron microscopic, x-ray diffraction, and dilatometric analyses. Alloy density and microhardness are measured. Alloy atomic hydrogen content is studied by vacuum heating. It is shown that hydrogen treatment improves cast alloy structural parameters and deformability, raises post-deformation strength by a factor of 1.3 - 1.4, and lowers linear expansion coefficient.