Feng Rui, Feng Bojun, Gao Michael C, Zhang Chuan, Neuefeind Joerg C, Poplawsky Jonathan D, Ren Yang, An Ke, Widom Michael, Liaw Peter K
Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN, 37996, USA.
Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
Adv Mater. 2021 Dec;33(48):e2102401. doi: 10.1002/adma.202102401. Epub 2021 Oct 8.
Refractory high-entropy alloys (RHEAs) show promising applications at high temperatures. However, achieving high strengths at elevated temperatures above 1173K is still challenging due to heat softening. Using intrinsic material characteristics as the alloy-design principles, a single-phase body-centered-cubic (BCC) CrMoNbV RHEA with high-temperature strengths (beyond 1000 MPa at 1273 K) is designed, superior to other reported RHEAs as well as conventional superalloys. The origin of the high-temperature strength is revealed by in situ neutron scattering, transmission-electron microscopy, and first-principles calculations. The CrMoNbV's elevated-temperature strength retention up to 1273 K arises from its large atomic-size and elastic-modulus mismatches, the insensitive temperature dependence of elastic constants, and the dominance of non-screw character dislocations caused by the strong solute pinning, which makes the solid-solution strengthening pronounced. The alloy-design principles and the insights in this study pave the way to design RHEAs with outstanding high-temperature strength.
难熔高熵合金（RHEAs）在高温下显示出广阔的应用前景。然而，由于热软化，在高于1173K的高温下实现高强度仍然具有挑战性。利用材料的固有特性作为合金设计原则，设计了一种具有高温强度（在1273K时超过1000MPa）的单相体心立方（BCC）CrMoNbV难熔高熵合金，其性能优于其他已报道的难熔高熵合金以及传统高温合金。通过原位中子散射、透射电子显微镜和第一性原理计算揭示了其高温强度的来源。CrMoNbV在高达1273K的温度下仍能保持高温强度，这源于其较大的原子尺寸和弹性模量失配、弹性常数对温度的不敏感依赖性，以及强溶质钉扎导致的非螺旋位错占主导地位，这使得固溶强化作用显著。本研究中的合金设计原则和见解为设计具有出色高温强度的难熔高熵合金铺平了道路。
