Hybrid friction stir channeling (HFSC) is a new friction stir-based method for producing internal, closed channels created simultaneously during welding of multiple metal plates. Differently from conventional friction stir channeling, that is only able to produce channels in a monolithic component, HFSC can be applied to complex structural systems involving multiple components made of similar or dissimilar materials. In this study, the channels manufactured by HFSC were open in a structural system made of AA5083, with one base plate of 5 mm thick, and one overlapping plate of 8 mm thick, used as a rib, containing the channel along conformal cooling path. The thermal performance of the HFSC channel is compared with a conventional channel, with similar shape and path, produced by milling. The channels being tested are part of an electronic device containing multiple heat sources. The HFSC channel presents 30 to 40% lower steady-state temperature and 33% higher cooling rate during the transient period than those of the milled version. Compared with the milled channel, the heat extraction capacity, per unit of mechanical pumping power, is higher for the HFSC channel. Surface roughness, microhardness, and microstructural analysis of HFSC channels are investigated to characterize the HFSC channel.

The Friction Stir Channelling (FSC) is a novel advanced solution for producing internal closed channels along any desired path with a constant or continuously modified shape along the path in a single manufacturing step. The channels are formed by continuous extraction of part of the stirred processed material into external flash. In this work, the performance of channels with the same shape and dimensions but produced by FSC and milling respectively, are compared using an experimental calorimeter setup with a focus on the influence of the geometrical features of the channels on the thermal efficiency. The investigation is implemented in a plate of AA5083-H111, with a thickness of 10 mm. The material properties of the channels produced by FSC are investigated with a microhardness field and optical microscopic analysis, assessing the thermomechanically processed and heat affected zones. The mechanical resistance of the channels produced by FSC is evaluated with an application of internal pressure up to 380 bar. The results show that the FSC enhanced the heat transfer by about 45 % compared with smoother milled channels. The optical microscopy shows evidence of a good consolidation of the solid state joining mechanisms activated during the FSC, with a small reduction of the hardness around the channel in the stirred zone and heat affected zone, being assisted by a harder top region at the ceiling of the channel.

No abstract