Ceramic nanoparticle-reinforced aluminium metal matrix composites (AMMCs) have superior mechanical properties compared with matrix alloys, exhibiting great potential in structural applications in industries such as the aerospace and automotive sectors. This research proposes a new method for distributing SiC nanoparticles in an aluminium matrix alloy by powder metallurgy. The mixing of aluminium powder and SiC nanoparticles was processed by a two-step procedure, which included ultrasound-assisted stirring and planetary agitation. After that, the mixing powder was subjected to compaction, sintering and extrusion. A blank sample and three composite sheets containing 1, 2 and 3 wt % SiC nanoparticles were prepared and the mechanical properties were investigated by micro-hardness and tensile tests. A scanning electron microscope (SEM) and electron back-scattered diffraction (EBSD) were used for microstructural analysis of the composite. Experimental results revealed that by adding 1, 2, 3 wt % SiC nanoparticles, hardness was increased by 26%, 34.5%, 40.0% and tensile strength was increased by 22.3%, 28.6% and 29.3%, respectively. The grain size of the aluminium matrix decreased with the addition of SiC nanoparticles. Moreover, a decrease of elongation was observed with the increasing weight fraction of SiC.

Microstructure evolution of 15 wt% boron carbide particle reinforced aluminum matrix composites (B₄C/Al composites) with titanium addition during liquid-stirring process was dynamically characterized in this paper. B₄C particles were rapidly dispersed under the mechanical stirring. Many B₄C clusters were formed in the melt before 20 min, but gradually scattered in matrix beyond 20 min, owing to further reactive wetting through interface reaction in addition to stirring. After rapid improvement, distribution uniformity slowly approached to completely uniform distribution during 20–55 min, even better than random distribution at 55 min. Interface reaction produced Al₃BC, TiB₂, and AlB₂ by B₄C erosion and Al₃Ti decomposition; however, AlB₂ only precipitated in matrix after long time stirring. The growth of TiB₂ transformed from a fine layer to discretely coarse crystals on the B₄C surface. Reaction mechanism and relationship between reactive wetting and particle dispersion were discussed.

The materials for artificial bone scaffolds have long been a focal point in biomaterials research. Tantalum, with its excellent bioactivity and tissue compatibility, has gradually become a promising alternative material. 3D printing technology shows unique advantages in designing complex structures, reducing costs, and providing personalized customization in the manufacture of porous tantalum fusion cages. Here we report the pre-clinical large animal (sheep) study on the newly developed 3D printed biomimetic trabecular porous tantalum fusion cage for assessing the long-term intervertebral fusion efficacy and safety. Porous tantalum fusion cages were fabricated using laser powder bed fusion (LPBF) and chemical vapor deposition (CVD) methods. The fusion cages were characterized using scanning electron microscopy (SEM) and mechanical compression tests. Small-Tailed Han sheep served as the animal model, and the two types of fusion cages were implanted in the C3/4 cervical segments and followed for up to 12 months. Imaging techniques, including X-ray, CT scans, and Micro CT, were used to observe the bone integration of the fusion cages. Hard tissue sections were used to assess osteogenic effects and bone integration. The range of motion (ROM) of the motion segments was evaluated using a biomechanical testing machine. Serum biochemical indicators and pathological analysis of major organs were conducted to assess biocompatibility. X-ray imaging showed that both the 3D-printed and chemical vapor deposition porous tantalum fusion cages maintained comparable average intervertebral disc heights. Due to the presence of metal artifacts, CT and Micro CT imaging could not effectively analyze bone integration. Histomorphology data indicated that both the 3D-printed and chemical vapor deposition porous tantalum fusion cages exhibited similar levels of bone contact and integration at 3, 6, and 12 months, with bone bridging observed at 12 months. Both groups of fusion cages demonstrated consistent mechanical stability across all time points. Serum biochemistry showed no abnormalities, and no significant pathological changes were observed in the heart, liver, spleen, lungs, and kidneys. This study confirms that 3D-printed and chemical vapor deposition porous tantalum fusion cages exhibit comparable, excellent osteogenic effects and long-term biocompatibility. Additionally, 3D-printed porous tantalum fusion cages offer unique advantages in achieving complex structural designs, low-cost manufacturing, and personalized customization, providing robust scientific support for future clinical applications. The translational potential of this paper is to use 3D printed biomimetic trabecular porous tantalum spine fusion cage with bone trabecular structure and validating its feasibility in large animal models (sheep). This study provides a basis for further research into the clinical application of the 3D printed biomimetic trabecular porous tantalum spine fusion cage.

We investigated the effect of vacancy formation on brittle (D0₂₂) to ductile (L1₂-like) transition in Al₃Ti using DFT calculations. The well-known pseudogap on the density of states of Al₃Ti migrates towards its Fermi level from far above, via a W − M co-doping strategy, where M is Si, Ge, Sn or Pb respectively. In particular, by a W − M co-doping the underline electronic structure of the pseudogap approaches an octahedral (L1₂: t_2g, e_g) from the tetragonal (D0₂₂: e_g, b_2g, a_1g, b_1g) crystal field. Our calculations demonstrated that (1) a W-doping is responsible for the close up of the energy gap between a_1g and b_1g so that they tend to merge into an e_g symmetry, and (2) all M-doping lead to a narrower gap between e_g and b_2g (moving towards a t_2g symmetry). Thus, a brittle to ductile transition in Al₃Ti is possible by adopting this W − M co-doping strategy. We further recommend the use of W-Pb co-doped Al₃Ti to replace the less anodic Al electrode in Al-battery, due to its improved ductility and high Al diffusivity. Finally this study opens a new field in physics to tailor mechanical properties by manipulating electron energy level(s) towards higher symmetry via vacancy optimization.