Biomaterial Database

High-content ductile coherent nanoprecipitates achieve ultrastrong high-entropy alloys. 2018

Yao-Jian Liang, and Linjing Wang, and Yuren Wen, and Baoyuan Cheng, and Qinli Wu, and Tangqing Cao, and Qian Xiao, and Yunfei Xue, and Gang Sha, and Yandong Wang, and Yang Ren, and Xiaoyan Li, and Lu Wang, and Fuchi Wang, and Hongnian Cai

School of Materials Science and Engineering, Beijing Institute of Technology, 100081, Beijing, China.

Precipitation-hardening high-entropy alloys (PH-HEAs) with good strength-ductility balances are a promising candidate for advanced structural applications. However, current HEAs emphasize near-equiatomic initial compositions, which limit the increase of intermetallic precipitates that are closely related to the alloy strength. Here we present a strategy to design ultrastrong HEAs with high-content nanoprecipitates by phase separation, which can generate a near-equiatomic matrix in situ while forming strengthening phases, producing a PH-HEA regardless of the initial atomic ratio. Accordingly, we develop a non-equiatomic alloy that utilizes spinodal decomposition to create a low-misfit coherent nanostructure combining a near-equiatomic disordered face-centered-cubic (FCC) matrix with high-content ductile Ni3Al-type ordered nanoprecipitates. We find that this spinodal order-disorder nanostructure contributes to a strength increase of ~1.5 GPa (>560%) relative to the HEA without precipitation, achieving one of the highest tensile strength (1.9 GPa) among all bulk HEAs reported previously while retaining good ductility (>9%).