Metallurgical and Materials Transactions A

, Volume 40, Issue 11, pp 2761-2771

The Serrated Flow Behavior of Mg-Gd(-Mn-Sc) Alloys

  • X. Y. FangAffiliated withDepartment of Materials Engineering, Monash UniversitySchool of Materials Science and Engineering, Central South University
  • , D. Q. YiAffiliated withSchool of Materials Science and Engineering, Central South University
  • , J. F. NieAffiliated withDepartment of Materials Engineering, Monash University Email author 

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The tensile deformation behavior of extruded samples of Mg-0.8 pct Gd and Mg-0.8 pct Gd-0.5 pct Mn-0.45 pct Sc (at. pct) alloys has been studied. Both alloys exhibit serrated flow when they are tensile tested at temperatures ranging from 150 °C to 300 °C and at strain rates of 1.67 × 10−4 s−1 to 1.67 × 10−2 s−1, and this serrated flow behavior is significantly affected by postextrusion heat treatments. Combined with observations made by transmission electron microscopy (TEM) and three-dimensional atom probe (3DAP), the serrated flow is attributed to dynamic interactions between solute atoms and gliding dislocations. It is suggested that Gd atoms in the solid solution matrix of magnesium are mainly responsible for the serrations in the two alloys. The additions of Mn and Sc to the Mg-Gd alloy strengthen the dynamic solute-dislocation interactions and lead to a lower critical strain and larger stress drops of the serrated flow in the Mg-Gd-Mn-Sc alloy.