熵-焓协同驱动的高熵合金组织调控与强韧化

吕昭平, 刘雄军, 吴渊, 蒋虽合, 雷智锋

Microstructural Regulation and Strengthening-Toughening of High-Entropy Alloys Driven by Entropy-Enthalpy Synergy

LU Zhaoping, LIU Xiongjun, WU Yuan, JIANG Suihe, LEI Zhifeng

图1 TiZrHfNb-O难熔高熵合金的力学性能及位错与有序间隙原子复合体的交互作用[11]

Fig.1 Mechanical properties of the TiZrHfNb-O refractory high-entropy alloy (HEA) and dislocation interactions with ordered interstitial complexes[11] (a) room-temperature tensile stress-strain curves for the as-cast TiZrHfNb (denoted as base alloy), (TiZrHfNb)98O2 (denoted as O-2), and (TiZrHfNb)98N2 (denoted as N-2) HEAs (σy is the yield strength (squares), σUTS is the ultimate strength (diamonds), and ε is the elongation (circles). Inset shows the corresponding strain hardening response (dσ / dε), where σ is stress) (b) changes in strength and ductility observed for the HEAs introduced here, relative to several types of established high-performance alloys (c) dislocations in the 8% strained O-2 HEA, imaged under {111}-type diffraction conditions (Dislocation pinning at ordered oxygen complexes (OOCs) is observed, which suppresses dislocation motion (red arrows). Inset indicates the direction of the diffraction vector) (d) aberration-corrected STEM-annular bright field (ABF) image of the local atomic structure near the dislocation pinning point (e) aberration-corrected STEM-ABF image of the local atomic structure at the pinning point (White arrows point to the oxygen atom columns around the pinned dislocation. Interstitial oxygen atoms are clearly seen in the red dotted square) (f) corresponding STEM-HAADF image for the [111]bcc crystal axis with differently adjusted contrast to reveal that the pinning effect is induced by OOCs (Red dotted zone indicates the (O, Zr, Ti)-rich region, that is, the OOC) (g) aberration-corrected STEM-ABF image of the local atomic structure away from the pinning point