In this work, the effect of vibration on the mechanical, corrosion and wear characteristics of AZ91 composite layers fabricated by a modified friction stir processing has been examined. The vibration was implemented by the motor into the fixture placed beneath the work-piece. It was observed that vibration could highly modify the microstructure and mechanical properties of the composite layer owing to the increase in strain rate, deformation, and expansion of the material flow zone. Tensile strength increased from around 203 MPa for the samples processed by friction stir process (FSP) to about 234 MPa for the samples processed by friction stir vibration process (FSVP). Furthermore, a more uniform distribution of reinforcement SiC particles with less agglomerated domains was achieved using FSVP. The FSVPed sample exhibited better wear resistance compared to the conventional FSPed sample and the base metal. In this study, the principal common wear mechanisms were delamination, oxidation, abrasion, and plastic deformation. It was also found out that both FSPed and FSVPed specimens experienced lower hydrogen evolution volume during the immersion time compared to the base metal. Finally, the corrosion resistance of FSVPed sample highly increased compared to the FSP and base metal.

In this article, the effect of vibration and cooling media on the friction stir welding of 5083Al alloy is investigated. The vibration was introduced by the motor into the fixture inserted under the workpiece while a cooling media (water and lubrication oil) flowed into a canal in the fixture beneath the weld path. A constant rotation speed of 1250 r/min and a traveling speed of 90 mm/min were used for all the welding conditions. The thermal analysis measured by several thermocouples indicated that friction stir vibration welding (FSVW) provided maximum temperature distribution in the workpiece, while friction stir welding with the water cooling exhibited the lowest temperature value. The microstructure observations were conducted by optical microscope, scanning electron microscopy, and transmission electron microscopy. The results indicated substantial grain refinement when vibration and water cooling were simultaneously applied during the friction stir welding process. The hardness values increased from 50 to around 78 (Hv) for friction stir welding and FSVW with water systems, respectively. The joint efficiency (the ratio of the joint strength to the base metal strength) of the joint fabricated by FSVW with water cooling was around 87%, while this quantity was about 66% for the friction stir welding joint. Fracture analysis indicated more ductile behaviors for the samples fabricated by FSVW with the coolant systems. Furthermore, the joint fabricated by FSVW with water cooling exhibited the best wear resistance among all the samples in a pin-on-disk wear test.