Loading...

Friction stir processing of an aluminum-magnesium alloy with pre-placing elemental titanium powder: In-situ formation of an Al3Ti-reinforced nanocomposite and materials characterization

Khodabakhshi, F ; Sharif University of Technology | 2015

1415 Viewed
  1. Type of Document: Article
  2. DOI: 10.1016/j.matchar.2015.08.016
  3. Publisher: Elsevier Inc , 2015
  4. Abstract:
  5. A fine-grained Al-Mg/Al3Ti nanocomposite was fabricated by friction stir processing (FSP) of an aluminum-magnesium (AA5052) alloy with pre-placed titanium powder in the stirred zone. Microstructural evolutions and formation of intermetallic phases were analyzed by optical and electron microscopic techniques across the thickness section of the processed sheets. The microstructure of the nanocomposite consisted of a fine-grained aluminum matrix (1.5 μm), un-reacted titanium particles (<40 μm) and reinforcement particles of Al3Ti (<100 nm) and Mg2Si (<100 nm). Detailed microstructural analysis indicated solid-state interfacial reactions between the aluminum matrix and micro-sized titanium particles to form Al3Ti intermetallic phase. The hard inclusions were then fractured and re-distributed in the metal matrix by the severe thermo-mechanical conditions imposed by FSP. Evaluation of mechanical properties by hardness measurement and uniaxial tensile test determined significant enhancement in the mechanical strength (by 2.5 order of magnetite) with a high ductility (~22%). Based on a dislocation-based model analysis, it was suggested that the strength enhancement was governed by grain refinement and the presence of hard inclusions (4 vol%) in the metal matrix. Fractographic studies also showed a ductile-brittle fracture mode for the nanocomposite compared with fully ductile rupture of the annealed alloy as well as the FSPed specimen without pre-placing titanium particles
  6. Keywords:
  7. Al3Ti ; Aluminum-magnesium alloy ; Intermetallic nanocomposite ; Aluminum alloys ; Brittle fracture ; Ductile fracture ; Friction ; Friction stir welding ; Grain refinement ; In situ processing ; Light metals ; Magnesium ; Magnesium alloys ; Magnesium powder ; Mechanical properties ; Microstructure ; Nanocomposites ; Powder metals ; Reinforcement ; Solid state reactions ; Tensile testing ; Titanium ; Titanium alloys ; Tribology ; Aluminum - Magnesium alloys ; Friction stir processing ; Materials characterization ; Microscopic techniques ; Microstructural analysis ; Reinforced nanocomposite ; Reinforcement particles ; Uniaxial tensile test ; Aluminum
  8. Source: Materials Characterization ; Volume 108 , October , 2015 , Pages 102-114 ; 10445803 (ISSN)
  9. URL: http://www.sciencedirect.com/science/article/pii/S1044580315003253