Effect of temperature on deformation mechanisms of AZ31 Mg-alloy under tensile loading

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:775

Article

Dessolier, Thibaut¹  Lhuissier, Pierre¹  Roussel-Dherbey, Francine²  Charlot, Frederic²  Josserond, Charles¹  Blandin, Jean-Jacques¹  Martin, Guilhem¹ 

[1] Univ Grenoble Alpes, SIMaP, Grenoble INP, CNRS, F-38000 Grenoble, France

[2] Univ Grenoble Alpes, Grenoble INP, CMTC, BP 75, F-38402 St Martin Dheres, France

关键词: In situ;    Magnesium alloys;    SEM;    Digital image correlation;    High-temperature;    Grain boundary sliding;   

DOI  :  10.1016/j.msea.2020.138957

来源: Elsevier

【 摘 要 】

Controlled in situ SEM tensile tests have been carried out between 200 and 300 degrees C at a constant strain rate of 5.10(-5) s(-1) to investigate the effect of temperature on deformation mechanisms operating in an Mg-3Al-1Zn (AZ31) Mg-alloy. Fiducial microgrids deposited using electron beam lithography are used to evidence grain boundary sliding as well as to determine the spatial strain heterogeneities as a function of temperature. Dislocation creep and grain boundary sliding coexist between 200 and 300 degrees C but their respective activity varies significantly as shown by the strain rate sensitivity value m which is about 0.2 at 200 degrees C but about 0.5 at both 250 and 300 degrees C. In addition, grain boundary sliding becomes predominant at 250 and 300 degrees C whereas its occurrence is relatively limited at 200 degrees C. Slip trace analysis shows that at 200 degrees C prism and pyramidal slip already exhibit a great activity. Spatial strain heterogeneities determined by digital image correlation (DIC) based on microgrid displacements develop during the early stage of plastic deformation and persist at larger strains. It is shown that the strain in the vicinity of grain boundaries intensifies when the temperature rises from 200 to 300 degrees C while the core of grains accommodates less deformation in agreement with the fact that grain boundary sliding is predominant at 250 and 300 degrees C.

【 授权许可】

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