Lattice-distortion dependent yield strength in high entropy alloys

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:784

Article

Li, Li¹  Fang, Qihong¹  Li, Jia¹  Liu, Bin²  Liu, Yong²  Liaw, Peter K.³ 

[1] Hunan Univ, State Key Lab Adv Design & Mfg Vehicle Body, Changsha 410082, Hunan, Peoples R China

[2] Cent South Univ, State Key Lab Powder Met, Changsha 410083, Peoples R China

[3] Univ Tennessee, Dept Mat Sci & Engn, Knoxville, TN 37996 USA

关键词: High-entropy alloys;    Lattice distortion effect;    Solute concentration;    Solid-solution strengthening;    Yield strength;   

DOI  :  10.1016/j.msea.2020.139323

来源: Elsevier

【 摘 要 】

High entropy alloys (HEAs) have attracted great attention due to their impressive properties induced by the severe lattice distortion in comparison to the conventional alloys. However, the effect of severe lattice distortion on the mechanical properties in face-centered-cubic (FCC) and body-centered-cubic (BCC) structured HEAs is still not fully understood, which are critically important to the fundamental studies as well as the industrial applications. Herein, an analytical model for predicting the solid-solution strengthening and the yield stress in FCC and BCC HEAs accounting for the lattice distortion is presented. Both the calculated solid-solution strengthening and the yield strength are compared to the experimental results, to verify the rationality of the built theoretical model. The numerical predictions considering the severe lattice-distortion effect agree well with the experimental results for both FCC and BCC HEAs, in terms of the yield strength and the solid-solution strengthening. Based on theoretical model, the constructed contour line of solid-solution strengthening can be used to evaluate the effect of elemental type on yield strength of HEAs, which provides guideline for discovering and screening the advanced HEAs. Furthermore, it has been identified the atomic-radius mismatch and solid-solution strengthening do not increase directly as the number of components increases in HEAs based on the theoretical analysis. In the Al-x-Cr-Co-Fe-Ni-Mn HEA system, the atomic-radius mismatch and shear-modulus mismatch induced by the added Al element govern the solid-solution strengthening, but this situation disappears in the Al-x-Hf-Nb-Ta-Ti-Zr HEA system. It is further confirmed that the effect of the atomic-radius mismatch on the solid-solution strengthening is obviously higher than effect of the shear-modulus mismatch, dominating the yield strength. These results provide an insight into the effect of severe lattice distortion on the yield strength, and demonstrate a theoretical framework for identifying the desired compositions to create the excellent HEAs.

【 授权许可】

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