Impact of surface gradient structures on mechanical properties of a dual-phase AlCrFe2(Ni0.85Co0.15)2 multi-component eutectic alloy

Abstract The multicomponent eutectic alloys (MCEAs) have demonstrated great potential applications in industrial fields owing to their excellent castability during solidification. The cast MCEAs can achieve a good strength-ductility synergy. However, they usually suffer from mechanical failure at surface due to high surface residual stress resulting from direct solidification. Here we introduce a surface treatment technique through electromagnetic induction heating (EMIH), by which the stress level at surface (−24 MPa) was significantly reduced compared to that of the base MCEA (+573 MPa) with a chemical composition of AlCrFe2(Ni0.85Co0.15)2. This EMIH treatment not only mitigates surface residual stress but also enhances tensile ductility by 30 % without sacrificing its yield strength. In contrast, surface gradient structure synthesized by surface mechanical grinding treatment (SMGT) exhibited a dual-phase nanostructure, together with a compressive residual stress that is an order of magnitude higher than that of the EMIH-processed MCEA. The SMGT-processed MCEA showed marginal improvement in its tensile ductility because of limited work hardening ability resulting from limited dislocation sources at surface. Our study envisages an approach to process MCEAs by surface treatment with relatively a low cost.