Effect of Intense Rolling and Folding on the Phase Stability of Amorphous Al-Y-Fe Alloys
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A systematic examination of the effect of intense deformation on the crystallization behavior of amorphous Al85Y10Fe5, Al86Y9Fe5, and Al88Y5Fe7 alloys demonstrated a strong composition dependence of the crystallization reactions at true strain levels of about −500 pct. Primary crystallization occurs during the deformation of the Al88Y5Fe7 alloy, but for the Al86Y9Fe5 and Al85Y10Fe5 alloys, deformation-induced crystallization is not observed at a true strain of about −500 pct. At strain levels of the order of −1200 pct, the Al85Y10Fe5 alloy develops regions with primary Al, which is not observed during thermal processing of the same amorphous alloy without deformation. In addition, at strain levels of −1200 pct, a deformed Al88Y7Fe5 sample displays strong microstructural heterogeneities. Transmission electron microscopy (TEM) analysis showed the presence of nanocrystal dispersions adjacent to shear bands with a total width of about half a micrometer. The results demonstrate that the phase selection during deformation-induced crystallization can deviate from the thermally-induced phase selection. Novel phases and microstructures can thus be obtained from the deformation processing of amorphous alloys.