High-temperature tensile behaviors of a bimodal-grained Mg-Mn-Ce alloy

In this work, the high-temperature tensile behaviors of an extruded Mg-0.9Mn-0.5Ce (wt%) alloy with bimodalgrained microstructure were investigated, and the tensile tests were conducted at 423 K - 523 K with the strain rate ranging from 6.0 x 10(-3) s(-1) to 1.5 x 10(-1) s(-1). It was found that the alloy exhibited a maximum fracture elongation of -156% and a highest strain-rate sensitivity exponent of 0.36 when deformed at 473 K. The softening effects generated by continuous dynamic recrystallization, the activation of < c + a > slipping on the pyramidal planes and grain boundaries migration collaboratively contributed to the high fracture elongation. As temperature increases to 523 K, microstructure stability was rapidly decreased and the deformation ability was severely restricted owing to the growth of grains, resulting in the adequate fracture elongation and low strainrate sensitivity exponent.