Tribotechnical properties modification of Al-Sn alloys by ECAP
The influence of ECAP on tribotechnical properties of Al-Sn alloys was investigated. It was established that their wear rate under dry friction on steel is reduced up to 18 ± 2% after pointed treatment while the friction coefficient does not depend on the ECAP numbers.
Microstructure and strength of a deformation processed Al-20%Sn in situ composite
An Al-20 vol% Sn metal-metal composite was deformation processed by extrusion, swaging, and wire drawing to a total true strain of 7.4, resulting in a microstructure with Sn filaments in an Al matrix. Both the size and spacing of the Sn filaments decreased as deformation processing progressed. The strength of these composites increased exponentially with the reduction in spacing of the Sn filaments. Immediately after deformation, the Sn second phase showed a convoluted, ribbon-shaped filamentary morphology, but the Sn filaments spheroidized during prolonged storage at room temperature. A thermodynamic assessment is presented for this spheroidization phenomenon.
Microstructural aspects of superplasticity
The microstructural aspects of the superplastic phenomenon are reviewed. The experimental results of a very large number of investigations are critically analysed in the context of: grain shape and size; grain growth; grain boundary sliding and migration, grain rotation and rearrangement; diffusion and dislocation activity. It is shown, that in spite of often conflicting evidence in the literature, a common pattern of microstructural behaviour emerges for all the materials and conditions investigated to date.