Strength and ductility enhancement in nanostructured AI6063 with a bimodal grain size distribution

6th International Conference on Nanomaterials by Severe Plastic Deformation

材料科学;化学

Oskooie, M Shakoori^1 ; Asgharzadeh, H.^1

Department of Materials Engineering, Faculty of Mechanical Engineering, University of Tabriz, PO Box 51666-16471, Tabriz, Iran^1

关键词: Bi-modal grain structure;    Bimodal grain-size distribution;    Deformation behavior;    Ductility enhancement;    Electron back scattered diffraction techniques;    High-energy mechanical milling;    Strength and ductilities;    Ultra-fine grained ( UFG);   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/63/1/012022/pdf
DOI  :  10.1088/1757-899X/63/1/012022

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

A bimodal grain structure comprising of ultrafine-grained (UFG) and coarse-grained (CG) regions was produced in Al6063 by means of powder metallurgy route. Nanocrystalline Al alloy powder was synthesized by high energy mechanical milling using a planetary ball mill under Ar atmosphere for 22.5 h. The as-milled powder was mixed with 30 vol.% unmilled powder and consolidated by extrusion at 450 °C with an extrusion ratio of 9:1. UFG and CG billets were also fabricated at the same condition by using milled and unmilled AI6063 powders, respectively. The grain structure was studied by scanning electron microscopy (SEM) and electron back-scattered diffraction (EBSD) techniques. The deformation behavior under uniaxial tension was investigated. The bimodal Al6o63 showed balanced mechanical properties, including enhanced yield and ultimate strength comparable UFG alloy with reasonable ductility analogous CG material. The fracture surfaces demonstrated a ductile fracture mode, in which the dimple size was related to the grain structure. The ductility enhancement mechanisms in nanostructured Al6o63 with bimodal grain structure were discussed.