Mechanical and Microstructural Characteristics of Superplastic Al-4.42Mg Aluminum Alloy

Abstract： The superplastic response of commercial 5083 alloy （Al-4. 42Mg） under uniaxial tension at strain rates ranging from 5 × 10-5 to 10-2s -1 in the temperature interval 400 -550℃ was systematically studied in this paper. The tension test was conducted on samples of rolling direction. The maximum elongation-to-failure of 486% was found at 500 % and strain rate of 10-4s-1. To identify the main characteristics of superplastic deformation and to determine the mechanism of superplastic deformation of the alloy, the microstructure and fracture of the alloy were analyzed as a function of strain, strain rate and temperature using optical microscopy （OM） and scanning electron microscopy （SEM）, the apparent strain rate sensitivity exponent ma and the apparent activation energy Qa were also studied. Based on the fracture analysis and the calculated data of m and Qa, it is suggested that the dominant deformation mechanism in the present alloy is grain boundary sliding （GBS） during the best deformation condition.