Effects of Zr/(Sc+Zr) microalloying on dynamic recrystallization, dislocation density and hot workability of Al-Mg alloys during hot compression deformation
(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Metal Materials Science and Engineering of Hunan Province, Central South University, Changsha 410083, China;
3. Applied Materials Science, Department of Engineering Science, Uppsala University, Uppsala 75121, Sweden)
2. Key Laboratory of Nonferrous Metal Materials Science and Engineering of Hunan Province, Central South University, Changsha 410083, China;
3. Applied Materials Science, Department of Engineering Science, Uppsala University, Uppsala 75121, Sweden)
Abstract: The deformation behavior and microstructure characteristics of Al-6.00Mg, Al-6.00Mg-0.10Zr and Al-6.00Mg-0.25Sc-0.10Zr (wt.%) alloys were investigated by hot compression tests and electron microscopy methods. The results show that after deforming under the maximum processing efficiency condition (673 K, 0.01 s-1), dislocation densities of Al-6.00Mg, Al-6.00Mg-0.10Zr and Al-6.00Mg-0.25Sc-0.10Zr alloys are 2.68×1016, 8.93×1016 and 6.1×1017 m-2, respectively. Their dynamic recrystallization fractions are 19.8%, 15.0% and 12.7%, respectively. Kernel average misorientation (KAM) analyses indicate that dislocation accumulation near grain boundaries is enhanced by adding Zr or Sc+Zr. Besides, the established hot processing maps, based on the dynamic material model (DMM), reveal that the addition of Zr or Sc+Zr can reduce the range of low-temperature unstable domain but expand the unstable domain at high temperatures and high strains. The experimental results further verify that under the testing deformation condition, only the Al-6.00Mg-0.25Sc-0.10Zr alloy cracks at 773 K and 1 s-1.
Key words: Al-Mg alloys; Sc; Zr; hot deformation; dislocation density; dynamic recrystallization