Evolution of deformation mechanisms and their orientation dependence in fine-grained Mg-3Gd during tension

• Published in: Journal of magnesium and alloys
• Main Authors: Hu, Faping, Yu, Tianbo, Chen, Hao, Han, Fang, Dai, Keshun, Qiu, Fangcheng, Xie, Weidong, Huang, Xiaoxu
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-04-2024
• Subjects: Deformation mechanisms; Fine-grained Mg alloy; Mechanical property; Orientation dependence; Fine-grained Mg alloy; Orientation dependence; Deformation mechanisms; Mechanical property
• ISSN: 2213-9567; 2213-9567
• DOI: 10.1016/j.jma.2024.03.019

•The evolution of various dislocations and twins in a fine-grained magnesium alloy were systematically investigated during plastic deformation.•Orientation dependent slip and twinning at different deformation stages were statistically studied by using a advanced characteristic technique combining EBSD and TEM.•Microstructural causes of excellent ductility and good strength of the fine-grained magnesium alloy were studied. In particular, the interactions of deformation mechanisms, grain size and grain crystal orientation were discussed, as well as their effects on mechanical properties.
Magnesium alloys usually exhibit poor ductility attributed to their intrinsic hexagonal close-packed (hcp) structure, which fails to provide sufficient independent slip systems for homogeneous deformation. Here we demonstrate that multiple deformation mechanisms can be activated with increasing tensile strain in a fine-grained Mg-3Gd with a weak basal texture. 〈c + a〉 slip, tension twinning and compression/double twinning exhibit a high orientation dependence at an early stage of deformation, whereas the orientation dependence becomes less obvious with further increasing strain. The high work hardening rate at the strain of 2%–5% is accompanied by the significant increase of 〈c + a〉 slip and tension twinning activities. The fine microstructure strongly restricts the activation and growth of twinning, resulting in a slow exhaust of tension twinning and thin compression twins. The restriction of twinning and the activation of profuse 〈c + a〉 slip near grain/twin boundaries, relaxing the stress concentration, sustain the homogeneous deformation to a high strain.