HRADILOVÁ Monika VŠCHT v Praze

Spoluautoři LEJČEK Pavel

Magnesium and its alloys are promising materials for transport industries as well as for medical application. Their mechanical and chemical properties can be significantly improved by decreasing grain size which can be achieved by dynamic recrystallization activated during hot deformation. Dynamic recrystallization can be distinguished as continuous or discontinuous. The present work is focused on the study of the mechanism of dynamic recrystallization modifying the microstructure of Mg–4Zn and Mg–4Zn–0.4Ca alloys (in wt.%) during the uniaxial compression at 240°C with constant strain rate of 0.001 s-1 and three different final strains of 0.09, 0.3 and close to 1. The development of microstructure was examined by light microscopy, scanning electron microscopy and transmission electron microscopy. Analyses of the microstructures showed that the grains were gradually fragmented with increasing strain which resulted generally in formation of the inhomogeneous structure constituted of fine dynamically recrystallized grains of several micrometres and coarse unrecrystallized initial grains. Besides, the deformation condition led to deformation-induced precipitation. To elucidate the main mechanism of dynamic recrystallization contributing to the grain refinement, the electron backscatter diffraction analysis was used. Preliminary results showed that the evolution of the microstructure was favourably influenced by Ca addition that evoked the formation of the second phase particles.

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