Microstructure evolution of 6061 O Al alloy during ultrasonic consolidation: An insight from electron backscatter diffraction

E. Mariani, E. Ghassemieh

Research output: Contribution to journalArticlepeer-review

67 Citations (Scopus)

Abstract

6061 O Al alloy foils were welded to form monolithic and SiC fibre-embedded samples using the ultrasonic consolidation (UC) process. Contact pressures of 135, 155 and 175 MPa were investigated at 20 kHz frequency, 50% of the oscillation amplitude, 34.5 mm s sonotrode velocity and 20 °C. Deformed microstructures were analysed using electron backscatter diffraction (EBSD). At all contact pressures deformation occurs by non-steady state dislocation glide. Dynamic recovery is active in the upper and lower foils. Friction at the welding interface, instantaneous internal temperatures (0.5-0.8 of the melting temperature, T), contact pressure and fast strain rates result in transient microstructures and grain size reduction by continuous dynamic recrystallization (CDRX) within the bonding zone. Bonding occurs by local grain boundary migration, which allows diffusion and atom interlocking across the contact between two clean surfaces. Textures weaken with increasing contact pressure due to increased strain hardening and different grain rotation rates. High contact pressures enhance dynamic recovery and CDRX. Deformation around the fibre is intense within 50 μm and extends to 450 μm from it.
Original languageEnglish
Pages (from-to)2492-2503
Number of pages12
JournalActa Materialia
Volume58
Issue number7
DOIs
Publication statusPublished - 01 Apr 2010

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