中國有色金屬學報(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 27 No. 5 May 2017 |
（1. College of Materials Science and Engineering, Hunan University, Changsha 410082, China;
2. Hunan Province Key Laboratory for Spray Deposition Technology and Application, Hunan University, Changsha 410082, China;
3. College of Materials Science and Engineering, Xi’an Technological University, Xi’an 710032, China）
Abstract:In as-cast Mg-2.1Gd-1.1Y-0.82Zn-0.11Zr (mole fraction, %) alloy, lamellar microstructures that extend from grain boundaries to the interior of α-Mg grains are identified as clusters of γ′ using a scanning transmission electron microscope equipped with a high-angle annular dark-field detector. Under a total strain-controlled low-cyclic loading at 573 K, the mechanical response and failure mechanism of Mg-2.1Gd-1.1Y-0.82Zn-0.11Zr alloy (T6 peak-aging heat treatment) were investigated. Results show that the alloy exhibits cyclic softening response at diverse total strain amplitudes and 573 K. The experimental observations using scanning electron microscopy show that the micro-cracks initiate preferentially at the interface between long-period stacking order structures and α-Mg matrix and extend along the basal plane of α-Mg. The massive long-period stacking order structures distributed at grain boundaries impede the transgranular propagation of cracks.
Key words: Mg-Gd-Y-Zn-Zr alloy; long-period stacking order structure; low-cycle fatigue at high temperature; crack initiation and propagation
