Single-phase solid-solution refractory high-entropy alloys (HEAs) show remarkable mechanical properties, such as their high yield strength and substantial softening resistance at elevated temperatures. Hence, the in-depth study of the deformation behavior for body-centered cubic (BCC) refractory HEAs is a critical issue to explore the uncovered/unique deformation mechanisms. We have investigated the elastic and plastic deformation behaviors of a single BCC NbTaTiV refractory HEA at elevated temperatures using integrated experimental efforts and theoretical calculations. The in situ neutron diffraction results reveal a temperature-dependent elastic anisotropic deformation behavior. The single-crystal elastic moduli and macroscopic Young’s, shear, and bulk moduli were determined from the in situ neutron diffraction, showing great agreement with first-principles calculations, machine learning, and resonant ultrasound spectroscopy results. Furthermore, the edge dislocation–dominant plastic deformation behaviors, which are different from conventional BCC alloys, were quantitatively described by the Williamson-Hall plot profile modeling and high-angle annular dark-field scanning transmission electron microscopy.

单相固溶耐火高熵合金（HEA）具有出色的机械性能，例如高屈服强度和在高温下的显着抗软化性。因此，深入研究体心立方（BCC）耐火HEA的变形行为是探索未发现/唯一变形机制的关键问题。我们使用综合的实验成果和理论计算方法研究了单个BCC NbTaTiV难熔HEA在高温下的弹性和塑性变形行为。原位中子衍射结果显示出温度依赖性的弹性各向异性变形行为。单晶弹性模量和宏观杨氏模量，剪切模量和体积模量由原位中子衍射确定，与第一性原理计算，机器学习和共振超声光谱学结果非常吻合。此外，通过Williamson-Hall曲线轮廓模型和高角度环形暗场扫描透射电子显微镜定量描述了不同于常规BCC合金的边缘位错-主要塑性变形行为。