In this study, a specific Mg–Zn–RE alloy membrane with 6 wt.% zinc and 2.7 wt.% rare earth elements (Y, Gd, La and Ce) was prepared to investigate implant degradation, transport mechanism and guide bone regeneration in vivo. The Mg-membrane microstructure and precipitates were characterized by the scanning electron microscopy (SEM) and the transmission electron microscopy (TEM). The Mg-membrane degradation process and effect on osteogenesis were investigated in a critical-sized rat calvarial defect model via micro-CT examination and hard tissue slicing after 2-, 5- and 8-week implants. Then, the distribution of elements in organs after 1-, 2- and 4-weeks implantation was examined to explore their transportation routes. Results showed that two types of precipitates had formed in the Mg–membrane after a 10-h heat treatment at 175 °C: γ-phase MgZn precipitation with dissolved La, Ce and Gd, and W-phase Mg₃(Y, Gd)₂Zn₃ precipitation rich in Y and Gd. In the degradation process of the Mg-membrane, the Mg matrix degraded first, and the rare earth-rich precipitation particles were transferred to a more stable phosphate compound. The element release rate was dependent on the precipitate type and composition. Rare earth elements may be transported mainly through the lymph system. The defects were repaired rapidly by the membranes. The Mg-membrane used in the present study showed excellent biocompatibility and enhanced bone formation in the vicinity of the implants.

To study the compressive mechanical properties and failure modes of TC11 titanium alloy fabricated by wire arc additive manufacturing (WAAM) technology in a large strain rate range at room temperature, the quasi-static and dynamic compression tests were carried out. In addition, optical microscopy (OM) and scanning electron microscopy (SEM) were employed to observe the metallographic structure and fracture morphology, respectively. The stress–strain curves in the range of 0.001 s⁻¹–4000 s⁻¹, original and post-deformation microstructures, macroscopic damage patterns, and microscopic fracture morphology were obtained at two different loading directions, including the scanning and deposition directions, respectively. In uniaxial compression experiments, the material showed little difference in mechanical properties between the scanning and deposition directions, exhibiting a strain rate strengthening effect. However, the strain rate sensitivity of the material under quasi-static loading conditions is much less than that under dynamic loading conditions. In addition, combining the stress–strain curve with the fracture morphology analysis, the plasticity in the scanning direction is better than in the deposition direction. Based on the experimental results, a modified Johnson–Cook (JC) constitutive model considering strain rate sensitivity and the effect of strain rate on strain hardening was proposed, and the parameters were determined using a Multiple Population Genetic Algorithm (MPGA). The obtained constitutive model is in good agreement with the experimental data, which can provide a reference for the engineering numerical calculation of TC11 titanium alloy for WAAM. This study also provides a fundamental databank for the application and design of WAAM TC11 alloy in the manufacturing of large and complex structural parts.

Ti–Ta impedance-graded coatings were prepared using cold spraying combined with hot isostatic pressing. Compared to the general Ti–Ta binary diffusion couple, the interdiffusion coefficient of as-sprayed Ti–Ta can be increased by approximately 25 times at 1100 °C due to grain refinement at the interface of the cold-sprayed particles. By the control of interdiffusion, pure Ta and pure Ti regions can remain in the materials after hot isostatic pressing at 900 °C. Hot isostatic pressing with capsulate reduced the porosity of the material efficiently to less than 0.02%. The strength of the as-sprayed Ti–Ta composite coating was significantly improved to 990.1 MPa, and the fracture strain reached 11.5%. The strengthening mechanism of Ti–Ta composite coatings relies primarily on the hindrance of dislocation slip by phase interfaces between α and β. Moreover, the macroscopic interfacial bonding strength of the graded material exceeds 881 MPa, which is comparable to that of bulk materials.