Defective structure, plastic properties, and reactivity of mechanically activated magnesium

Abstract

The genesis of a defective structure (particle size, size of coherent scattering regions (CSRs), dislocation concentrations, and two types of deformation and twin stacking defects (SDs)) of magnesium during its mechanical activation in a vibrating mill in the presence of liquid additions was studied by X-ray diffraction (XRD) analysis, microscopy, and adsorption (BET) method. The dynamic mechanical properties were checked for the activated samples using a K-44-2 vertical impact machine. The ability of magnesium to be oxidized in air was checked by heating it in the cell of a differential scanning calorimeter. At mechanical activation doses of less than 5 kJ/g, the accumulation of chaotically arranged dislocations and deformation SDs was accompanied by an increase in the plasticity of the material. At higher doses, polygonization of dislocations led to a drastic decrease in the CSR size and dislocation run, leading to embrittlement of the material. The changes in the mechanical properties were confirmed by symbatic changes in the outer particle size and showed themselves on the pressure oscillograms during the impulse loading of pressed Mg layers. Mechanical activation led to an increase in the level of oxidation of magnesium with oxygen, but did not affect the temperature of the start of oxidation. A method for activating magnesium with additions was suggested and led to the formation of highly disperse magnesium samples with the oxidation temperature lowered by 150°C.