Faceted Kurdjumov-Sachs interface-induced slip continuity in the eutectic high-entropy alloy, AlCoCrFeNi2.1

Recently, the eutectic high-entropy alloy (EHEA), AlCoCrFeNi2.1, can reach a good balance of strength and ductility. The dual-phase alloy exhibits a eutectic lamellar microstructure with large numbers of interfaces. However, the role of the interfaces in plastic deformation have not been revealed deeply. In the present work, the orientation relationship (OR) of the interfaces has been clarified as the Kurdjumov-Sachs (KS) interfaces presenting < 111 >(B2) parallel to < 110 >(FCC) and {110}(B2) parallel to {111}(FCC) independent of their morphologies. There exist three kinds of interfaces in the EHEA, namely, (321)(B2)parallel to(112)(FCC), (01 (1) over bar)(B2)parallel to(332<())over bar>(FCC), and (23 (1) over bar)(B2) parallel to(552)(FCC). The dominating (321)(B2)parallel to(112)(FCC) interface and the secondary (01 (1) over bar)(B2)parallel to(33 (2) over bar)(FCC) interface are both non-slip planes and atomistic-scale faceted, facilitating the nucleation and slip transmission of the dislocations. The formation mechanism of the preferred interfaces is revealed using the atomistic geometrical analysis according to the criteria of the low interfacial energy based on the coincidence-site lattice (CSL) theory. In particular, the ductility of the dual-phase alloy originates from the KS interface-induced slip continuity across interfaces, which provides a high slip-transfer geometric factor. Moreover, the strengthening effect can be attributed to the interface resistance for the dislocation transmission due to the mismatches of the moduli and lattice parameters at the interfaces. (C) 2020 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

The study reveals the orientation relationship of the interfaces in EHEA and emphasizes the important roles of the dominant and secondary interfaces in nucleation and slip transmission of dislocations, which impact the ductility and strength of the alloy.