The role of the melt properties in the formation of supersaturated nanostructured solid solutions of transition metals in aluminum

Abstract

Metallographic, X-ray diffraction and electron microscopy were used to study the phase compositions and structure of rapidly solidified Al- alloys with transition metals (Zr, Fe, Cr) subjected to severe plastic deformation by torsion under a high quasi-hydrostatic pressure (HPT). It was established that upon HPT a number and a size of aluminides decrease with increasing in a degree of deformation. For example, the maximum effect of deformation-induced dissolution of the particles is observed in the case where they have a dendritic structure and are about one micrometer in size. Upon HPT the supersaturation of α-phase increases by a factor of 2.5. in rapidly solidified Al-Cr and Al-Cr-Zr alloys and by a factor of 10 in rapidly solidified Al-Fe alloys. After HPT all alloys have ultrafine-grained (UFG) Al-based matrix with grain size of 70-200 nm and high hardness of 2 GPa.