Dynamic recrystallization mechanisms during hot compression of Mg-Gd-Y-Nd-Zr alloy
(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education,
Central South University, Changsha 410083, China;
3. Defense Technology Research and Technology Center, China Aerospace Science and Industry Corporation,
Beijing 100854, China)
2. Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education,
Central South University, Changsha 410083, China;
3. Defense Technology Research and Technology Center, China Aerospace Science and Industry Corporation,
Beijing 100854, China)
Abstract: Hot compression tests were conducted on a homogenized Mg-7Gd-4Y-1Nd-0.5Zr alloy at 450 °C and a strain rate of 2 s-1. Dynamic recrystallization (DRX) mechanisms were investigated by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM) systematically. The crystallographic orientation information is obtained through electron back-scattering diffraction (EBSD). The result shows that the flow stress firstly reaches a peak rapidly followed by declining to a valley, and then increases gradually again when the alloy is compressed to a strain of -1.88. DRX related to tensile twins is extensively observed at small strains, resulting in an evident grain refinement. DRX grains first nucleate along the edges of twin boundaries with about 30° á0001？ off the twin parents. While at large strains, conventional continuous DRX (CDRX) is frequently identified by the formation of small DRX grains along the original grain boundaries and the continuously increasing misorientation from the centre of large original grains to the grain boundaries. Evidence of particle-stimulated nucleation (PSN) is also observed in the present alloy.
Key words: Mg-RE alloy; hot compression; twin; dynamic recrystallization mechanism