Papers by Author: I.G. Brodova

Abstract: Structural and phase transformations in V95 (type of A7075) alloy upon high pressure torsion (HPT) up to high strain and upon dynamic channel angular pressing (DCAP) were studied using electron microscopy (TEM, SEM) and x-rays diffraction. It was established that the nanostructure with average grain size of 80-55 nm and hardness value of 2.5 GPa is formed by HPT at strain of e=5.5-6.4. It was shown the hardening metastable phase MgZn2 precipitates from supersaturated α-solid solution during dynamic deformation aging; its quantity grows with increasing of strain. Ultra fine grained structure with high- angle boundaries is formed in V95 alloy after already 2 cycles of DCAP. The average grain size is 200 nm in DCAP samples.

Abstract: Metallographic, X-ray diffraction and electron microscopy were used to study the phase compositions and structure of rapidly solidified the Al- alloys transition metals (Zr, Fe, Cr) subjected to severe plastic deformation (SPD) by torsion under a high quasi-hydrostatic pressure. It was established that upon SPD a number and a size of aluminides decrease with increasing a degree of deformation. For example, the maximum effect of deformation - induced dissolution of the particles are observed in the case where they have a dendritic structure and are about one μm in size. Upon SPD the supersaturation of α-phase increases by a factor of 2.5. (for rapidly solidified Al-Cr and Al-Cr-Zr alloys) and by a factor of 10 (for rapidly solidified Al-Fe alloy). After SPD all alloys have submicrocrystalline (SMK) Al-based matrix with grain size of 100-200 nm and high hardness of 2 GPa. The thermal stability of SMK deformed materials and some specific features of post deformation phenomena as an aging and a recrystallization were investigated.