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 (≈1.3 µm) and homogeneously distributed second‐phase particles. Elongations are all above 500% within a wide high‐temperature range of 708–758 K at 1 × 10−1 s−1, and an elongation of 549% at 1 × 10−1 s−1 is achieved at 758 K. 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. A fine‐grained Mg–Y–Nd alloy is prepared by submerged friction stir processing. Due to its fine microstructure and high thermal stability, which are beneficial to grain boundary sliding during superplastic deformation, excellent high‐strain‐rate superplasticiy is achieved in this material, with an elongation of 549% at 1 × 10−1 s−1 and 758 K.