Effect of treatment conditions on parameters of nanocrystalline structure in Al-based alloys

Abstract

Formation of aluminum nanocrystals in light Al90Y10 and Al87Ni8Gd5 amorphous alloys at heating and deformation was studied by X-ray diffraction and electron microscopy methods. High pressure torsion and multiply rolling were used for the deformation influences. The average size of the nanocrystals induced by deformation was found to be lower than that formed during the heat treatment. Combined treatment (deformation+annealing) leads to the formation of nanocrystals of intermediate size. Increasing the deformation degree leads to an increase in the fraction of the nanocrystalline phase. The dependence of the microhardness of amorphous - nanocrystalline structure on the deformation degree was measured. Increasing the deformation degree (and thus rising fraction of the nanocrystalline phase) increases the microhardness of the alloys. The value of the microhardness, close to a record for light Al-based alloys is obtained for amorphous-nanocrystalline Al87Ni8Gd5 alloy.