Implementing high entropy alloy synthesis via friction stir processing: Simultaneous solid-state alloying and ultra-refinement of copper

• Published in: Vacuum Vol. 222; p. 113042
• Main Authors: Lone, Nadeem Fayaz, Bajaj, Dhruv, Gangil, Namrata, Abidi, Mustufa Haider, Chen, Daolun, Arora, Amit, Siddiquee, Arshad Noor
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2024
• Subjects: Alloying; Coincident site lattice boundaries; Copper; Friction stir processing; Grain refinement; Alloying; Coincident site lattice boundaries; Copper; Friction stir processing; Grain refinement
• ISSN: 0042-207X; 1879-2715
• DOI: 10.1016/j.vacuum.2024.113042

Using the multi-principal element based high entropy alloy (HEA) concept, single-step ultra refinement and solid-state alloying of Cu with NiTi, Y, Fe, Cr, and Co were achieved simultaneously for the first time via friction stir processing (FSP). A bimodal microstructure with an average grain size smaller than 1.5 μm was attained. The microstructure consisted of inter-dispersed regions of high and low density of geometrically-necessary dislocations. The fraction of high-angle grain boundaries was observed to increase from ∼33% in the unstirred region to ∼80% in the processed alloy. Intercalated bands having sharp variations in grain size were formed in conjunction with the bimodal microstructure. The entropic stabilization due to addition of diverse elements assisted multi-faceted heterogeneity and grain refinement along. This study paves the way for the development of HEAs via FSP. •Using the HEA based concept, solid state alloying of Cu with NiTi, Y, Fe, Cr, and Co, performed for the first time via FSP.•Ultra-refined microstructure with a bimodal distribution of grains.•Interwoven domains of low and high density of geometrically necessary dislocations (GNDs).•Intercalated bands in the processed regions exhibited sharp variation in grain size and alloying.