Structural-Phase Transformation in Rapidly Quenched Al–Ni–Y Ribbons under Thermal and Pressure Effects

Abstract

Comparative investigations of the crystallization of rapidly quenched Al₉₀Y₁₀ and Al₈₇Ni₈Y₅ ribbons under thermal and deformation effects are carried out by the methods of differential scanning calorimetry and X-ray structural analysis. It is shown that during continuous heating, crystallization of the rapidly quenched Al₉₀Y₁₀ and Al₈₇Ni₈Y₅ ribbons begins with the formation of a supersaturated solid solution based on α-Al. Moreover, for upon the subsequent heating of the Al₉₀Y₁₀ ribbon, the transition to the crystalline state proceeds through an intermediate stage to form the metastable phase, Al₄Y. It is shown that under the action of severe plastic deformation by high-pressure torsion (HPT), at a pressure of 3 GPa with rotation from 0 to 12 revolutions, complete crystallization of these rapidly quenched ribbons does not occur. Crystallization of the Al₉₀Y₁₀ ribbon initiated by deformation proceeds with the formation of the Al₄Y metastable phase (after 1 revolution) and the Al₂Y phase (after 4 revolutions), while the formation of the latter is not observed in the process of continuous heating of the initial ribbon. Crystallization of the Al₈₇Ni₈Y₅ ribbon under the action of HPT proceeds with the formation of α-Al crystals after 1 revolution.