Strengthening mechanisms in ultrafine grained Al-Mg-Si alloy processed by hydrostatic extrusion - Influence of ageing temperature

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

卷:669

Article

Chrominski, Witold¹  Wenner, Sigurd²  Marioara, Calin D.³  Holmestad, Randi²  Lewandowska, Malgorzata¹ 

[1] Warsaw Univ Technol, Fac Mat Sci & Engn, Woloska 141, PL-02507 Warsaw, Poland

[2] Norwegian Univ Sci & Technol NTNU, Dept Phys, N-7491 Trondheim, Norway

[3] SINTEF Mat & Chem, N-7465 Trondheim, Norway

关键词: Aluminium;    Ultrafine grained materials;    Precipitation strengthening;    Strengthening mechanisms;    Transmission electron microscopy;   

DOI  :  10.1016/j.msea.2016.05.109

来源: Elsevier

【 摘 要 】

Microstructure of hydrostatically extruded Al-Mg-Si alloy was studied by the combination of electron backscattered diffraction and transmission electron microscopy. Three different grain types which feature various defects arrangements were detected. Post deformation ageing at two temperatures caused different precipitation phenomena which were strongly dependent on type of grain boundaries in the considered grain types. Thus, a combination of plastic deformation and ageing resulted in a material with complex microstructure. Based on transmission electron microscopy observations, contributions of different strengthening mechanisms were estimated and compared to experimental results. A good agreement between obtained data points confirmed that depending on grain type, different strengthening mechanisms are operative and the overall strength is a sum of hardening given by each of them. Ageing of ultrafine grain structure results in efficient precipitation strengthening. On the other hand ageing causes annihilation of low and high angle grains boundaries in which leads to softening of investigated material. This effect cannot be compensated by precipitation hardening. (C) 2016 Elsevier B.V. All rights reserved.

【 授权许可】

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