Influence of phase morphology on mechanical properties of dual-phase eutectic high-entropy alloys

The dual-phase eutectic high-entropy alloys (EHEA) have been attracted by their exceptional properties, which are achieved by combining two or more phases with different distribution patterns, which can strongly affect material interaction. However, there are not many reports on deformation behavior and tensile properties of the dual-phase EHEA with phase distributed intentionally. Therefore, this work uses Molecular Dynamic (MD) simulation to investigate the tensile model of dual-phase herringbone FeCoNiAl EHEA with various layer thicknesses and layers’ fold angles, along with a comparison to monocrystalline , dual-phase lamellae specimens. The results reveal that high tensile strength is achieved by alternately arranging hard and soft phases in lamellae layers perpendicular to the tensile direction or herringbone pattern morphology, especially the highest tensile strength of over 13 GPa achieved in the case of herringbone sample with a BCC layer thickness of 50 Å and layers’ fold angle of 55 0 . On the other hand, parallel phase layers in horizontal lamellae workpieces exhibit the lowest strength but allow for improved uniform elongation and remain slightly lower than that of a monocrystalline FCC case due to the inhibition of dislocation growth caused by the alternating hard phases. Meanwhile, the dual-phase herringbone morphologies provide uniform elongation up to 13.3 % due to the interlaminar stress dispersion across multiple slip systems of FCC content and the containment-reorientation atom migration function of the structural interfaces. Stress-strain curve (a), elastic modulus, and uniform elongation of various dual-phase phase morphology (b); shear strain distribution of interior atoms (c), and displacement vector (d) under the stretching process; tensile strength and uniform elongation of various phase distribution pattern, tensile strength (f 1 ), and elastic modulus (f 2 ) are functions of layers’ fold angles and layer thicknesses while stretching the herringbone workpiece of FeNiCoAl eutectic high-entropy alloy. • BCC layers resist shear for strength, meanwhile, FCC layers transfer strain with minimal blocking at structural interfaces. • Dual-phase herringbone shows BCC-level strength and better elongation than both FCC and BCC monocrystals. • Interphases block dislocations and guide atom migration, helping reduce necking in herringbone structures. • Raising fold angles boosts modulus and strength, peaking at 50Å of BCC layer thickness despite general thickness trends.