Fig. 1 Schematic comparison of “damage prevention” and “damage healing” mechanisms。。

Fig. 2 Schematic overview of the self-healing mechanisms in metallic materials

Fig. 3 a Time evolution of the volume fraction of Au-rich precipitates for the Fe-Au alloy with 0%, 8% and 24% pre-strain during aging at 550 °C; b comparison of the creep curves for the Fe-1at.%Au and Fe-1at.%Cu model alloys (100 MPa, 550 °C); c micrograph of filled and partially filled cavities and micro-cracks after creep; d examples (top view) showing cavities with different filling ratios (FR). Reprinted with permission from Refs. [27, 30, 32]

Fig. 4 Examples of partially filled creep cavities in the Fe-W alloy sample after a creep time of 0.50 tR (550 °C, 160 MPa). The figure shows representations of four partially filled cavities from different angles rendered from high-resolution data with a voxel size of 30 nm. The applied stress is normal to the top view. Reprinted from Ref. [33] with permission from Elsevier

Fig. 5 Schematic diagram of a shape memory alloy self-healing system. Reprinted with permission from Ref. [47]

Fig. 6 a SEM image of the crack before and after healing in nickel; b electron backscatter diffraction (EBSD) image of the central part of the healed crack; c tensile stress-strain curves of the sample without crack and the cracked samples with and without healing process. Reprinted with permission from Ref. [52]

Fig. 7 Healing of cellular nickel subjected to tensile loading near failure, the photograph and SEM micrograph and stress-strain data of samples before and after healing. Reprinted with permission from Ref. [54]

Fig. 8 Distortion and self-healing of coherent twin boundaries (CTBs). An initially straight CTB a1 formed a curved puddle upon its encountering of a mobile interstitial loop a2. The puddle on CTB was replaced by two undulations a3. By 25 s a4, the CTB was nearly recovered (self-healed). b1-b6 Schematics illustrate the capturing of defect clusters by CTB and their self-healing mechanism. Reproduced with permission from Ref. [68]. Copyright (2015) American Chemical Society

Fig. 9 Evolution of the amorphous-crystal phase boundaries and the irradiation-induced vacancies (blue spheres) in nanocrystal grain and vacancy-like defects (brown spheres) in amorphous matrix, of the intercepted ANA model. Various snapshots of this model are shown, at the simulation time of a 0.0 ps, b 0.2 ps, c 0.4 ps, d 0.6 ps, e 0.8 ps, f 1.3 ps, g 4.0 ns, h 20.0 ns. i The black, the red and the blue lines denote the phase boundaries at the simulation time of 0.0 ps, 0.8 ps and 20.0 ns, respectively. Reprinted from Ref. [71] with permission from Elsevier

Fig. 10 HAADF mode TEM image of the Fe-Au alloy a and the Fe-Cu alloy b with corresponding elemental mapping after He+ irradiation (550 °C, 1.27 dpa); c comparison of radiation swelling along the projected radiation depth for the irradiated Fe-Au ad Fe-Cu alloys; d binding energies of complexes Au-Vn ($E_{\text{b}}^{{{\text{Au}} - V_{n} }}$), Cu-Vn ($E_{\text{b}}^{{{\text{Cu}} - V_{n} }}$), Au-HenVn ($E_{\text{b}}^{{{\text{Au}} - {\text{He}}_{n} V_{n} }}$) and Cu-HenVn ($E_{\text{b}}^{{{\text{Cu}} - {\text{He}}_{n} V_{n} }}$) plotted as a function of the vacancy cluster size n. Reprinted from Refs. [73, 74] with permission from Elsevier