Poida A. The Kinetics of Structural Changes and Phase Transitions in Specimens of Aluminum Alloys 1460 and AMg6 Deformed Superplastically under High Homologous Temperatures

The object of study are the structural changes and phase transitions which take place during the superplastic deformation of aluminum alloys 1460 and AMg6; the aim is the determination of mechanical behavior features, of the kinetics of structural changes and phase transitions which take place during the superplastic flow of aluminum alloys 1460 and AMg6 specimens, deformed under high homological temperatures; the methods are the mechanical tests of specimens by tension in the air in a creep mode at a permanent true flow stress; metallographical, topographical and fractographical investigations; raster electron microscopy, structural x-ray analysis and energy-dispersion x-ray microanalysis; differential thermal analysis; results: temperature-strain rate conditions of high-temperature structural superplasticity effect of specimens of alloys 1460 and AMg6, deformed in the air in a mode of creep, and the phenomenological parameters of their flow are experimentally determined. The features of the change ofthe medium size of grains and of their morphology change during the superplastic deformation of samples are determined. The most probable reasons of partial melting of alloys 1460 and AMg6, which occurs during the deformation of their specimens in conditions of high-temperature structural superplasticity, are considered. In interface cavities, microcracks and on the fracture surfaces of deformed specimens fibrous formations with different morphology are revealed. Mechanisms of their formation and development during superplastic deformation are considered. The effective activation energies of superplastic flow of specimens of the investigated alloys are determined. The reasons and mechanisms of the fracture of alloys 1460 and AMg6 specimens are established; the field is the physics of solid sate.