Development of Ti-Zr-Hf-Y-La high-entropy alloys with dual hexagonal-close-packed structure

TiZrHfYLa0.2 high-entropy alloys (HEAs) with dual hexagonal-closed-packed (HCP) structures were designed based on the concept of liquid phase separation (LPS) and segregation for enhancing the immiscibility of the constituent elements. The LPS leads to a particular solidification microstructure on the free surface side and Cu-hearth contacted area in the ingots. The dual HCP structures with equi-axis Ti-Zr-Hf dendrite and Y-La-rich interdendrite were observed at most regions of the arc-melted ingots. The mixing enthalpy among the constituent elements and predicted phase diagrams constructed by the Materials Project were effective for the alloy design of the HEAs with dual HCP structures. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd.