Papers by Keyword: S₁-Phase

Abstract: The fine-fibrous nonrecrystallized structure determines substantial tensile property anisotropy of hot rolled 1424 alloy sheets. In the present work the possibility of producing a fully recrystallized structure in cold rolled sheets was investigated. To improve a technological plasticity a cold rolling was performed after preliminary annealing of hot rolled sheets. The technological plasticity was studied by means of determination a critical deformation degree at plane strain compression at room temperature. The phase composition of hot rolled and annealed sheets was investigated using TEM and X-ray analysis. The uniform fine-grained and fully recrystallized structure in sheets was obtained after rolling with preliminary annealing at 350-380°C and final solid solution treatment. After the indicated above annealing the maximum volume fraction of the equilibrium S1-phase precipitates was observed in the alloy. After cooling in air from the annealing temperature it was found a very small quantity of δ′-phase and after slow cooling with the furnace this phase was practically absent. The fully recrystallized structure in sheets provides a substantial decrease of the tensile property anisotropy in three d irections.

Abstract: The structure of Al-Li-Mg system alloy 1420, containing a small quantity of Sc, Zr, Ti was investigated in cast, homogenized, hot-pressed, quenched and aged conditions, using the methods of optical metallography, transmission electron microscopy and X-ray examination. An existence of areas, having fine grains (20-30 nm)- "Ultrafine Grain areas"(UFGA) was observed in all the investigated conditions. UFGA are located on the boundaries, sub boundaries and S1(Al2MgLi) phase particles. UFGA can also form near the particles of crystallization origin. These areas have a complex phase composition. Inside the UFGA the particles of S1(Al2MgLi) phase and also δnon-phase, investigated in [1] are always present whereas δ'(Al3Li) precipitations are absent. These areas are formed during crystallization and hot deformation. Their composition changes during the treatment. The nature of these changes is considered.