Effect of Nano-Particle Addition on Grain Structure Evolution of Friction Stir-Processed Al 6061 During Postweld Annealing

Abstract

The fabrication of nano-composites is quite challenging because uniform dispersion of nano-sized reinforcements in metallic substrate is difficult to achieve using powder metallurgy or liquid processing methods. In the present study, Al-based nano-composites reinforced with Al 2 O 3 particles have been successfully fabricated using friction stir processing. The effects of nano-Al 2 O 3 particle addition on grain structure evolution of friction stir processed Al matrix during post-weld annealing were investigated. It was revealed that the pinning effect of Al 2 O 3 particles retarded grain growth and completely prevented abnormal grain growth during post weld annealing at 470 °C. However, abnormal grain growth can still occur when the composite material was annealed at 530 °C. The mechanism involved in the grain structure evolution and the effect of nano-sized particle addition on the mechanical properties was discussed therein.

Relationship between welding conditions, abnormal grain growth and mechanical performance in friction-stir welded 6061-T6 aluminum alloy

“…Very often [8,[18][19][20][21]23,34,35,51,54], the abnormal microstructural coarsening in friction-stir welded materials is explained in terms of the Humphreys cellular model [55,56]. According to this theory, the abnormal annealing behavior is attributed to a combined effect of drastic grain refinement and dissolution of second-phase particles both occurring during FSW.…”

The Evolution of Abnormal Grains during the Heating Stage of a Post-Weld Solution Treatment in a Friction-Stir-Welded 2519 Aluminium Alloy

“…The abnormal grain growth in these alloys has been explained by the Humphreys cellular theory [38,39], which considers the simultaneous effects of grain refinement and precipitate dissolution that occur during FSW [24,25,[39][40][41][42][43][44][45]. However, many aspects of this phenomenon remain unclear.…”

Fabrication of AA6061-T6/Al<sub>2</sub>O<sub>3</sub> Reinforced Nanocomposite Using Friction Stir Welding

“…A number of contributions were tested for producing the metal matrix composites (MMC) via FSP [12][13][14]. In their works, attempts were made by the researchers for fabricating layers on the composite surface of parent metal in which no weldment of parent material took place via friction stir processing.…”