V.K. Portnoy

Formation of Ni-Al and Ni-Al-X Phases by Mechanical Alloying

The Ni-Al phases were synthesized in the composition range 40-85 at. % Ni by mechanical alloying (MA) of elemental component mixtures. MA of Ni-Al powders produces the B2 phase in the range 40 – 61 at. % Ni and a solid solution Ni(Al) – in the range 65-85 at. % Ni. Milling of Ni62.5Al37.5 composition results in formation of the B2 and Ni(Al) phases mixture. Formation of a supersaturated solid solution for 65-75 at. % Ni were accompanied by appearance of B2 phase at the intermediate MA stage. Ball milling of Ni and Al powder mixtures of the compositions corresponded to intermetallics NiAl and Ni3Al, with a 5 at. % addition of X=Ti, Mo or Nb, where the third element was substituted for Ni (Ni45Al50X5 and Ni70Al25X5), Al (Ni50Al45X5 and Ni75Al20X5) or both (Ni47.5Al47.5X5 and Ni71.25Al23.75X5) was performed. The regularities of influence of the third components on the final structure of the as-milled and annealed alloys were observed. The preferred sublattices for X additions in B2 and L12 intermetallic phases were determined.

The Effect of Heat Treatment and Mn, Cu and Cr Additions on the Structure of Ingots of Al-Mg-Si-Fe Alloys

Phase transformations in 6XXX alloys with Mn, Cu and Cr additions have been studied in the process of homogenization annealing at different temperatures. The continuous cooling transformation diagrams of decomposition of solid solution during the cooling of ingots from the homogenization temperature have been plotted. The effect of the cooling rate after homogenization on the properties of ingots during extrusion has been studied.

Rheological Analogies of Superplastic and Viscous-Plastic Materials Flow

There are presented original experimental results of studying rheological behavior of Vitralloy 1 (Zr41Ti14Cu12.5Ni10Be22.5), which shows in the certain strain rate range stable linear viscous (Newtonian) flow. Comparative analysis of these results and the results related to other superplastic alloys as well as to crystallizing metallic melts has been carried out.