Segida O. Formation and decomposition of the anomalous supersaturated solid solution of Al-Sc, Al-Zr and Al-Hf prepared by rapid quenching from liquid state

The study of effect of the cooling rate, quenching temperature of melt, nature and concentration of alloying element on the anomalous supersaturation of binary hypereutectic Al-Sc and hyperperitectic Al-Zr, Al-Hf alloys, the study of decomposition and stability of the "fan" structures formed by crystallization are presented in the thesis. It has been established that the quenching temperature effects on structural and phase states of Al-Sc, Al-Zr and Al-Hf alloys rapidly quenched from liquid state. The quenching from 1400 C leads to formation of the anomalous supersaturated solid solutions. Alloys quenched from 1000 C have structures of cooperative growth. The phase composition of these structures depends on the diffusive mobility of atom of alloying element. It has been determined that alloys are decomposed with formation of strengthening Al3X (Sc, Zr, Hf) phase ordered by the Cu3Au-type during initial stage of aging.