Lee Chanho, Chou Yi, Kim George, Gao Michael C, An Ke, Brechtl Jamieson, Zhang Chuan, Chen Wei, Poplawsky Jonathan D, Song Gian, Ren Yang, Chou Yi-Chia, Liaw Peter K
Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN, 37996-2100, USA.
Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
Adv Mater. 2020 Dec;32(49):e2004029. doi: 10.1002/adma.202004029. Epub 2020 Nov 2.
Severe distortion is one of the four core effects in single-phase high-entropy alloys (HEAs) and contributes significantly to the yield strength. However, the connection between the atomic-scale lattice distortion and macro-scale mechanical properties through experimental verification has yet to be fully achieved, owing to two critical challenges: 1) the difficulty in the development of homogeneous single-phase solid-solution HEAs and 2) the ambiguity in describing the lattice distortion and related measurements and calculations. A single-phase body-centered-cubic (BCC) refractory HEA, NbTaTiVZr, using thermodynamic modeling coupled with experimental verifications, is developed. Compared to the previously developed single-phase NbTaTiV HEA, the NbTaTiVZr HEA shows a higher yield strength and comparable plasticity. The increase in yield strength is systematically and quantitatively studied in terms of lattice distortion using a theoretical model, first-principles calculations, synchrotron X-ray/neutron diffraction, atom-probe tomography, and scanning transmission electron microscopy techniques. These results demonstrate that severe lattice distortion is a core factor for developing high strengths in refractory HEAs.
严重畸变是单相高熵合金（HEAs）的四种核心效应之一，对屈服强度有显著贡献。然而，由于两个关键挑战，通过实验验证在原子尺度晶格畸变与宏观尺度力学性能之间建立联系尚未完全实现：1）开发均匀单相固溶体高熵合金存在困难；2）描述晶格畸变以及相关测量和计算存在模糊性。通过热力学建模与实验验证相结合，开发出了一种单相体心立方（BCC）难熔高熵合金NbTaTiVZr。与先前开发的单相NbTaTiV高熵合金相比，NbTaTiVZr高熵合金具有更高的屈服强度和相当的塑性。利用理论模型、第一性原理计算、同步辐射X射线/中子衍射、原子探针断层扫描和扫描透射电子显微镜技术，从晶格畸变的角度对屈服强度的增加进行了系统和定量的研究。这些结果表明，严重的晶格畸变是难熔高熵合金实现高强度的核心因素。
