Different lattice distortion effects on the tensile properties of Ni-W dilute solutions and CrFeNi and CoCrFeMnNi concentrated solutions

The lattice distortion of a solute primarily occurs because its atomic size and chemical bonding are different from those of neighboring atoms. The lattice distortion effects in conventional and high-entropy alloys are different; however, a detailed investigation on these effects has yet to be conducted. To fill this research gap, this study produced face-centered cubic-structured dilute solutions (Ni, Ni–2 at.% W, and Ni–4 at.% W) and concentrated solutions (equiatomic CrFeNi and CoCrFeMnNi) and compared their tensile properties. For the two W-containing alloys, lattice distortion occurred only around the large and strong W atoms. However, for the two concentrated solutions, which had a similar interelement atomic size and shear modulus to the aforementioned alloys, lattice distortion occurred at all lattice sites. These two types of lattice distortion had significantly different effects on tensile properties. The strength and ductility of the alloys with a high concentration of distorted lattice points were higher than those of the alloys with a low concentration of distorted lattice points, although the alloys with a low concentration of distorted lattice points had a larger nominal atomic size difference and shear modulus difference. The mechanisms underlying the evolution of different mechanical properties under different types of lattice distortion were examined for the dilute and concentrated alloys. Moreover, the universal solid solution strengthening mechanism was observed.