Superplastic deformation behavior in commercial magnesium alloy AZ61

Abstract

Superplastic behavior of a commercial magnesium alloy, AZ61, has been investigated. Tensile tests were carried out at temperatures ranging from 573 to 673 K and strain rates ranging from 10-5 to 10-3s-1. Superplastic behavior was observed in the low strain rate range and, especially, a maximum elongation-to-failure of 461% was obtained at 648 K at a strain rate of 3×10-5s-1. The alloy showed a high strain rate sensitivity exponent of 0.5. Inspection of the specimen surface after deformation revealed direct evidence for grain boundary sliding (GBS). In addition, the distribution of misorientation angles was essentially unchanged during superplastic flow. From these results, it was concluded that the dominant deformation mechanism was GBS.