Fabrication of AA6061/AlCoCrFeNi high-entropy alloy surface composite through flame spraying and friction stir processing

• Published in: Materials chemistry and physics Vol. 333; p. 130358
• Main Authors: Aali, E., Rabiei, N., Sarkari Khorrami, M., Soltani, R.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2025
• Subjects: AA6061 aluminum alloy; Friction stir processing; High-entropy alloy; Surface composite; Thermal spraying; Thermal spraying; Friction stir processing; AA6061 aluminum alloy; High-entropy alloy; Surface composite
• ISSN: 0254-0584
• DOI: 10.1016/j.matchemphys.2025.130358

The fabrication of metal-matrix composites by means of friction stir processing (FSP) has been the subject of many researches. However, the majority of works employed a method in which added particles are preplaced within a groove cut at the surface of a substrate. In the present study, a new method for the fabrication of AA6061/AlCoCrFeNi high-entropy alloy (HEA) surface composite has been introduced that could be more practical in industries. For this purpose, AlCoCrFeNi HEA powders were produced by mechanical alloying (MA) under various processing times, affecting the extent of alloying as well as the final size of particles. The powders were deposited on the surface of the substrate employing thermal spraying process, followed by FSP. The results indicated that a dual-phase of BCC and FCC crystal structure was formed during MA after 30 h of milling. During thermal spraying, Al and Cr partially left the alloyed powders to form oxides. This issue is more prominent in the case of MA for 30 h. Some cracks and porosities were also observed in the sprayed coating. The FSP was found practicable to eliminate these defects. Additionally, it caused the HEA powders to disperse well in the stir zone, achieving surface composite. Microstructural examinations revealed the diffusion of Al from matrix to the HEA phases, possibly leading to an increase in the entropy value of the distributed phase. Microhardness values of the stir zone was approximately three times more than those of the base metal in the case of MA under 20 h due to the new structure obtained. •Aluminum-matrix composite reinforced by high-entropy alloy particles was produced by thermal spraying and FSP.•HEA particles were obtained with mechanical alloying under different processing times.•Increasing the milling time led to formation of finer HEA particles, more susceptible to oxidation during thermal spraying.•FSP was found suitable for distribution of HEA particles within the Al matrix, obtaining surface composite.•The microhardness of processed sample was three times more than that of the substrate.