INFLUENCE OF TEMPERATURE AND STRAIN RATE ON SUPERPLASTICITY KINETICS OF COMPOSITE AZ61-F MAGNESIUM MATERIALS

Micromechanisms of fracture of AZ61-F composites in the zone of quasi-superplastic deformation were analyzed and quantified in this work. Deformation of AZ61-F magnesium alloys with 1 wt.% of Al₂O₃ phase was tested at a temperature of 473 K and different strain rates. It was shown that at the temperature of 473 K and the highest strain rate applied from 1<em>× </em>10<em>⁻</em>² to 1 <em>× </em>10<em>⁻</em>⁴ s<em>⁻</em>¹, a significant growth of ductility was observed. The mean dimples diameter of the ductile fracture decreased with the decreasing strain rate. The grain size of 0.7 μm was reached by severe plastic deformation using equal channel angular pressing (ECAP). Secondary Mg₁₇Al₁₂ and Al₂O₃ phases were identified. The maximum strain was reached at the temperature of 473 K and strain rate of 1 <em>× </em>10<em>⁻</em>⁴ s<em>⁻</em>¹.

Micromechanisms of Fracture of Magnesium Based Composite After Superplastic Deformation

The micromechanisms of fracture of AZ61 + 1 wt. % Al2O3 composite in the zone of superplastic deformation was analysed and quantified in this work. The specimens were tested at temperature of 200°C at different strain rates. Changing the strain rate, from 1x10-2 s-1 to 1x10-4 s-1, a significant growth of ductility was observed. At maximum value of superplasticity the fracture was transcrystalline ductile with dimples of two size categories. Based on the statistical analysis of fracture micromechanisms at the elevated temperature and strain rates of 10-0- 1x10-4 s-1 hyperbolic dependency was depicted according to Gurland - Plateau theory.