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As powerful techniques for multidisciplinary research, the neutron and synchrotron radiation sources have the advantages of deep penetration and high brilliance, providing advanced and powerful tools for characterizing microstructures and revealing deformation/damage micromechanisms of materials. For research on engineering materials, such as advanced steel, superalloy, titanium alloy, and aluminum alloy, it is necessary to develop advanced in-situ microstructure and stress characterization methods to reveal the evolution of the multiscale microstructures and stress fields during preparation and service and investigate the micromechanical behaviors, including deformation damage and phase transformation, under complex external factors, such as temperature, stress, electric, and magnetic fields. The basic principles of quantitative characterization of texture and multiscale stress using neutron and X-ray diffraction (XRD) techniques were introduced in this paper. The global development and status of advanced characterization techniques based on neutron and synchrotron radiation sources were expounded. The advantages of neutron and synchrotron radiation techniques were also analyzed. The application of neutron and synchrotron-based XRD techniques in the research of structural engineering materials and components, thermoelastic martensitic transformation, and new structural materials were reviewed. The use of neutron diffraction and HE-XRD techniques on structural engineering materials mainly focuses on multiphase microstructure evolution, intergranular and interphase stress distribution in elastic/plastic zone during deformation, and temperature/stress-induced phase transformation behaviors. The microscopic stress measurement is crucial for verifying the micromechanical model of engineering structural material, which is closely related to the texture evolution during the deformation and phase transformation. The simultaneous acquisition of microscopic stress and macroscopic stress can provide essential data for the service reliability and failure evaluation standards of engineering structural materials/components. Using the µXRD characterization method with submicron resolution, through the combination of monochromatic and polychromatic diffraction analysis, the precise characterization of large stress gradient and slight orientation gradient, caused by the dislocation structures inside the grain, can be realized to achieve submicron damage evaluation. The research on thermoelastic martensitic transformation by neutron scattering (diffraction) and HE-XRD technology includes external field-assisted thermoelastic martensitic transformation, narrow hysteresis thermoelastic martensitic transformation, and colossal elastocaloric effect. Neutron diffraction and HE-XRD techniques have advantages in studying emerging structural materials, such as high-entropy alloys and heterogeneous materials, which often have complex microstructures and exhibit unique mechanical behaviors and are important for revealing their deformation and damage mechanisms. The neutron and synchrotron-based technology, combined with in-situ environmental devices, can be used to measure and analyze the multiscale microstructures/stress and service damage behaviors of key engineering components in a near-service environment. Finally, the development and application of characterization techniques based on neutron and synchrotron radiation sources have prospects.

Objective To evaluate the clinical application and surgical efficacy of the chimeric perforator flap pedicled with the descending branch of the lateral circumflex femoral artery and the lateral thigh muscle flap for the reconstruction of the large area of deep wound in foot and ankle. Methods Clinical data of 32 cases who underwent chimeric anterolateral thigh perforator flap to repair the large area of deep wound of the foot and ankle from January 2015 to December 2018 were retrospectively analyzed. The sizes of the defects ranged from 18 cm × 10 cm to 35 cm × 20 cm, with exposed tendon and bone and/or partial defects and necrosis, contaminations, accompanied by different degrees of infection. Following the radical debridement and VSD, chimeric anterolateral thigh perforator flap was employed to repair the deep wounds according to the position, site and deep‐tissue injury of the soft‐tissue defects. The skin flap and muscle flap were fanned out on the wound, and single‐ or two‐staged split‐thickness skin grafting was performed on the muscle flap. The operation time and blood loss were recorded. The survival and healing conditions of the operational site with chimeric anterolateral thigh perforator flap were evaluated post‐operationally. Complications at both recipient site and donor site were carefully recorded. Results The mean time of the operation was 325.5 min and average blood loss was 424.8 mL. Among the 32 cases, two cases developed vascular crisis, which were alleviated with intensive investigation and treatment; Four cases suffered from partial necrosis of the flap or skin graft on the muscle flap or on the residual local wound, which were improved after treatment of further dressing change and skin grafting. Another four cases experienced post‐traumatic osteomyelitis accompanied by bone defect were treated with simple bone grafting or Mesquelet bone grafting at 6–8 months after wound healing. Postoperatively, the wounds were properly healed, and the infection was effectively controlled without sinus tract forming. Overall, all 32 cases received satisfactory efficacy, without influencing subsequent functional reconstruction, and observed infection during the 12–36 months post‐operational follow‐up. Conclusion The chimeric perforator flap pedicled with the descending branch of the lateral circumflex femoral artery and the lateral thigh muscle flap provides an effective and relative safe procedure for the repair of a large area of deep wound in the foot and ankle, particularly with irregular defect or deep dead space.

Residual stress exists extensively in biological and engineering structures. Here we report that residual stress can be engineered to significantly enhance the strength and ductility of gradient materials. In-situ synchrotron experiments revealed that the strongest strain hardening occurred in the layer with the highest compressive residual stress in a gradient structure. This layer remained elastic longer than adjacent layers during tension, producing high hetero-deformation induced stress to increase strength and enhancing work hardening even after the disappearance of the compressive stress to increase ductility. This finding provides a new paradigm for designing gradient structures for superior mechanical properties.