Grain boundary engineering-induced grain refinement and texture evolution in FeNiCoCrTi high-entropy alloys

This study systematically investigates the influence of trace Y additions on grain refinement mechanisms and texture evolution in the Fe₃₀Ni₃₀Co₂₅Cr₁₀Ti₅ high-entropy alloy. The results reveal a critical Y content at 0.3%. Below this threshold, Y-rich precipitates form within the alloy, exhibiting a semi-coherent interface with the matrix characterized by a lattice mismatch of 8.8%. These precipitates act as effective heterogeneous nucleation sites and simultaneously induce compositional undercooling, collectively promoting significant grain refinement and resulting in a weak, randomly oriented rotated cubic texture. Conversely, when the Y content exceeds the critical value (0.5%), excessive solute segregation causes substantial compositional undercooling, which facilitates the accelerated growth of a limited number of grains with preferred orientations. This leads to abnormal grain coarsening and the development of strong mixed Goss and Brass textures. By elucidating the combined effects of heterogeneous nucleation and compositional undercooling, this research highlights the pivotal role of Y addition in grain refinement within high-entropy alloys, providing a theoretical foundation for precise microstructural and performance optimization of these alloys through grain boundary engineering.