Microstructural evolution and its effects on the mechanical properties of fine-grained Mg-3Gd during tension

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 855; p. 143877
• Main Authors: Hu, Faping, Chen, Hao, Liu, Ronghai, Wei, Guobing, Qiu, Fangcheng, Li, Hanyi, Xie, Weidong
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 10-10-2022; Elsevier BV
• Subjects: Deformation effects; Deformation mechanism; Deformation mechanisms; Dislocation density; Electron backscatter diffraction; Evolution; Fine grain size; Gadolinium; Grain boundaries; Grain size; Hardening rate; Magnesium alloys; Magnesium base alloys; Mechanical properties; Microstructural evolution; Microstructure; Plastic deformation; Recrystallization; Work hardening; Yield strength; Fine grain size; Microstructural evolution; Work hardening; Magnesium alloys; Deformation mechanism
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2022.143877

Recrystallized Mg-3 wt. % Gd with an average grain size of 4 μm was prepared and tensioned under different strains (2%, 5%, 10%, and 20%) to investigate the evolution of the deformation mechanism and its effects on the mechanical properties of fine-grained Mg alloy during plastic deformation. The microstructure of the alloy has been characterized using electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). The results show that the dislocation density was ∼0.67 × 1014 m−2 at 2% strain, which was accompanied by a few tension twins and <c + a> dislocations. Upon increasing the strain to 5%, the dislocation density was significantly increased to 1.77 × 1014 m−2, which contributes approximately 60% of the flow stress increment when compared to that observed at 2% strain. Meanwhile, tension twins were more frequently observed, while <c + a> dislocations were detected in most of the grains. The dislocation density was slightly increased to 2.31 × 1014 m−2 in the 10% tensile-deformed Mg-3Gd sample, while other strengthening sources became increasingly important. The proportion of low angle grain boundaries (LABs) was almost tripled and compression or double twins are observed. The dislocation density became saturated at ∼2.00 × 1014 m−2 and the proportion of LABs remained unchanged upon further increasing the strain to 20%, although compression or double twins were more frequently detected, which resulted in a low work hardening rate.