Microstructure and physical and mechanical properties of the Al$_{90}$Gd$_{10}$ binary alloy after barothermal treatment

Using the microindentation, X-ray diffraction, optical microscopy, and electron microscopy methods, the microstructure and bulk physical and mechanical properties (hardness, reduced elastic modulus, plasticity index, elastic recovery parameter) of two samples of the Al$_{90}$Gd$_{10}$ binary hypereutectic alloy (hereinafter, formula indices correspond to at.%) are studied. The first sample is obtained by rapid cooling of the melt at a rate of 1000 degree/s at a high pressure of 10 GPa; the hardening temperature is 1800 K. The second sample is obtained by pressing the original sample with a high pressure of 5 GPa without melting. Compared to the intial sample, the microstructure of both samples is crushed and compacted. The structure of the initial sample is comprised of two equilibrium phases of $\alpha$-Al and Al$_3$Gd. In the sample prepared without melting, a phase with composition Gd$_{55}$Al$_{45}$ is found in addition to the $\alpha$-Al and Al$_3$Gd phases; in the sample prepared with melting, a phase with composition Al$_{92}$Gd$_8$ is found. Features of the structure morphology and changes in the phase composition of the samples prepared under high pressure lead to changes in the physical and mechanical properties of the studied alloy.