High-Strain-Rate Superplasticity in Mg-Y-Nd Alloy Prepared by Submerged Friction Stir Processing

Superplastic tensile behavior of Mg-Y-Nd alloy prepared by submerged friction stir processing (SFSP) is investigated. Microstructure of the SFSP alloy is mainly composed of fine-grained magnesium grains (approximate to 1.3 mu m) and homogeneously distributed second-phase particles. Elongations are all above 500% within a wide high-temperature range of 708-758K at 1x10(-1)s(-1), and an elongation of 549% at 1x10(-1)s(-1) is achieved at 758K. The excellent high-strain-rate superplasticity is attributed to the fine-grained microstructure and high thermal stability during superplastic deformation. Grain boundary sliding is the dominated deformation mechanism during superplastic deformation, and the specimens failed through cavity coalescence.