HIGH STRAIN RATE SUPERPLASTICITY OF WE43 MAGNESIUM ALLOY

Superplastic behavior of ultrafine-grained (UFG) magnesium alloy Mg-4Y-3RE (wt%) prepared by equal channel angular pressing (ECAP) was investigated at high strain rates. Eight passes through ECAP resulted in grain refinement down to similar to 340 nm and formation of a high volume fraction of fine secondary phase particles located at the grain boundaries and triple-points. Dense distribution and high thermal stability of these particles provided excellent thermal stability of the UFG microstructure even at high temperatures. The microstructure of the material was investigated by transmission electron microscopy. Superplastic behavior was investigated in the temperature range of 350-450 degrees C and strain rate range of 10(-2) s(-1) - 10(-1) s(-1). The results revealed high strain rate superplasticity in the investigated material. Deformation to fracture exceeded 1000 % for several deformation conditions, even at the strain rate of 10(-1) s(-1).