Solidification Microstructures in 3d-Transition Metal High Entropy Alloys with Cu Element

Abstract

In this study, high-entropy alloys (HEAs) with Cu as the main constituent element were investigated, focusing on the distribution of Cu in the ingots. Based on the taxonomy of HEAs, those with Cu as the casting material were classified as (1) HEAs whose main constituent elements were 3d transition metals, such as Co, Cr, Fe, Mn, Ni, and Cu (3d-HEAs), and (2) high-entropy (HE) brasses based on the Cu–Zn alloy system and HE bronzes based on Cu–Sn and/or Cu–Al alloy systems. In the case of 3d-HEAs with Cu, the distribution of Cu in the ingots exhibited the following tendency: (1-1) segregation from the dendrite to the residual liquid, resulting in the formation of Cu-rich interdendritic regions in the ingots; (1-2) liquid-phase separation resulting in the formation of a Cu-rich liquid, which formed a macroscopically phase-separated structure; and (1-3) the dispersion of fine Cu precipitates embedded in the solid solution matrix.

 

This Paper was Originally Published in Japanese in J. Japan Inst. Copper 60 (2021) 167–175. Some figures were corrected for the revision from gray-contrast images to color-contrast images. Reference 50 and Fig. 4 were slightly modified.

Fig. 2 Relationship between the main constituent elements and periodic table for various HEAs including 3d-transition-metal HEAs (3d-HEAs), refractory HEAs (RHEAs), HEAs for metallic biomaterials (BioHEAs), and lightweight HEAs (LW-HEAs), focusing on Cu elements. (a) 3d-HEAs, RHEAs, BioHEAs and LW-HEAs, (b) HE brasses, and HE bronzes.