Structure, mechanical properties and strengthening mechanisms of rapidly quenched Al-based ribbons consolidated by high pressure torsion processing

The influence of high-pressure-torsion (HPT) processing on the structure and hardness of laminated disks consolidated from rapidly solidified ribbons of Al86Ni9Gd5 and Al95.8Mn3.8Fe0.4 alloys with amorphous and crystalline structures, respectively, as well as from their combination was studied using X-ray diffraction (XRD) analysis, scanning electron microscopy and microhardness measurements. The effect of the HPT deformation by unconstrained and constrained schemes on the changes of concentration of supersaturated Al-based solid solution in the as-prepared Al95.8Mn3.8Fe0.4 ribbon was found. The experimentally established increase in hardness of disks consolidated from crystalline ribbons as a function of the level of deformation was quantitatively analyzed within the additive model. The contributions of grain boundary, dislocation and solid solution strengthening mechanisms were determined using the values of sizes of coherently scattering domains, microstrains and solid solution concentration found from the XRD data. The changes in the hardness of disks consolidated from Al86Ni9Gd5 amorphous ribbons due to the formation of a nanocomposite structure were measured. An increase in the hardness of disks consolidated from amorphous and crystalline ribbons above the hardness value that harder disks with a nanocomposite structure was established and a possible reason of this effect caused by additional microstrains in the crystalline material due to mixing, was discussed.