Mechanical Properties and Deformation Mechanisms of Mg-Gd-Y-Zr Alloy at Cryogenic and Elevated Temperatures

摘要

In this study, mechanical properties and deformation mechanisms of Mg-Gd-Y-Zr alloy at temperatures ranging from 77 K to 523 K have been investigated. The effects of temperature on the mechanical properties, deformation mechanism, and fracture mechanism are discussed. The results show that the strengths of alloy decrease gradually while the elongations increase progressively with increasing temperature. The maximum ultimate tensile strength of the alloy as high as 442 MPa is obtained at 77 K. As the temperature increases from 77 K to 523 K, the ultimate tensile strength of the alloy decreases from 442 MPa to 254 MPa and the elongations increase from 6.3 to 28.9 gradually. The study verifies that the deformation at 77 K is predominated by basal slip and deformation twinning system. At 223 K, lots of twins emerge primarily at grain boundaries. At 373 K, all dislocations are proved to be aOE (c) a > dislocations. At 523 K, although basal slip is still the dominant deformation mechanism, non-basal slip systems also become activate.