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Microstructural features, texture and strengthening mechanisms of nanostructured AA6063 alloy processed by powder metallurgy

Asgharzadeh, H ; Sharif University of Technology

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  1. Type of Document: Article
  2. DOI: 10.1016/j.msea.2011.01.082
  3. Abstract:
  4. Nanostructured AA6063 (NS-Al) powder with an average grain size of ~100. nm was synthesized by high-energy attrition milling of gas-atomized AA6063 powder followed by hot extrusion. The microstructural features of the consolidated specimen were studied by transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) techniques and compared with those of coarse-grained AA6063 (CG-Al) produced by hot powder extrusion of gas-atomized powder (without using mechanical milling). The consolidated NS-Al alloy consisted of elongated ultrafine grains (aspect ratio of ~2.9) and equiaxed nanostructured grains. A high fraction (~78%) of high-angle grain boundaries with average misorientation angle of 33° was noticed. Microtexture evaluation by plotting pole-figures and orientation distribution function (ODF) analysis showed Copper and P texture components for both the consolidated Al alloys. Tensile test at room temperature and microhardness measurement revealed that a significant improvement in the strength of AA6063 alloy is obtained through refinement of the grain structure. The strengthening mechanisms are discussed based on the dislocation-based models. The role of high-angle and low-angle grain boundaries on the strengthening mechanisms is discussed
  5. Keywords:
  6. Aluminum alloys ; Microstructure ; Nanostructured materials ; Strengthening mechanism ; Texture ; Al alloys ; Attrition milling ; Average grain size ; Coarse-grained ; Electron backscatter diffraction technique ; Gas-atomized powders ; Grain structures ; High angle grain boundaries ; High energy ; Hot extrusion ; Low angle grain boundaries ; Mechanical milling ; Micro-texture ; Microhardness measurement ; Microstructural features ; Misorientation angle ; Nano-structured ; Orientation distribution function ; P textures ; Powder extrusion ; Room temperature ; Strengthening mechanisms ; TEM ; Tensile tests ; Ultra fine grain ; Aluminum ; Aspect ratio ; Distribution functions ; Extrusion ; Grain boundaries ; Grain refinement ; Grain size and shape ; Mechanical alloying ; Metal analysis ; Microstructural evolution ; Milling (machining) ; Powder metallurgy ; Strengthening (metal) ; Tensile testing ; Textures ; Transmission electron microscopy ; Tensile strength
  7. Source: Materials Science and Engineering A ; Volume 528, Issue 12 , 2011 , Pages 3981-3989 ; 09215093 (ISSN)
  8. URL: http://www.sciencedirect.com/science/article/pii/S0921509311001043