The use of additive manufacturing technology for the lightweight design of complex lattice structures is becoming increasingly popular, but research on lattice structure design and strength evaluation still relies on the visual comparison of stress distributions and lacks quantitative assessment data. Given this perspective, this study explored the effects of structural parameters (relative density, cell size, and sample size) on the compressive strength of diamond lattice structures prepared by Stereolithography (SLA) and revealed the underlying mechanisms through stress distribution simulations and the calculation of characteristic stress distribution parameters (structural efficiency and stress concentration coefficient). The results showed that a greater relative density can increase structural efficiency, but it hardly affects the stress concentration coefficient, and smaller cell sizes and larger sample sizes increase the stress concentration coefficient without affecting the structural efficiency. Lattice structures with a greater relative density, higher structural efficiency, and a larger stress concentration coefficient exhibit higher compressive strength according to the lattice strength formula, which indicates that lattice strength is determined by the product of structural efficiency, stress concentration coefficient, relative density, and material strength. The relevant conclusions could guide the analysis of lattice stress distribution and the design of lattice structures.

The titanium matrix composites (TMCs) fabricated via Directed Energy Deposition (DED) effectively overcome the issue of coarse columnar grains typically observed in additively manufactured titanium alloys. In this study, systematic annealing heat treatments were applied to in situ (TiB + TiC)/Ti-6Al-4V composites to refine the microstructure and tailor mechanical properties. The results reveal that the plate-like α phase in the as-deposited composites gradually transforms into an equiaxed morphology with increasing annealing temperature and holding time. Notably, when the annealing temperature exceeds 1000 °C, significant coarsening of the TiC phase is observed, while the TiB phase remains morphologically stable. Annealing promotes decomposition of acicular martensite and stress relaxation, leading to a reduction in hardness compared to the as-deposited state. However, the reticulated distribution of the TiB and TiC reinforcement phases contributes to enhanced tensile performance. Specifically, the as-deposited composite achieves a tensile strength of 1109 MPa in the XOY direction, representing a 21.6% improvement over the as-cast counterpart, while maintaining a ductility of 2.47%. These findings demonstrate that post-deposition annealing is an effective strategy to regulate microstructure and achieve a desirable balance between strength and ductility in DED-fabricated titanium matrix composites.

A comprehensive study was carried out to investigate the effects of Fe addition (0–0.9 wt.%) on the microstructure evolution and mechanical properties of Ti-6Al-4V alloys. The results indicate that Fe addition has a significant refinement effect on the microstructure of titanium alloys; specifically, 0.9 wt.% Fe addition can lead to a 47.37% decrease in the width of lamellar α. The modulus also decreases by 18.89% with the increase in the Fe content, being 91.40 GPa in Ti-6Al-4V-0.9Fe. And the microhardness and wear resistance are improved due to Fe addition. In addition, the constitutive equation of the Fe content and the elastic compliance coefficient were calculated, which can better describe the relationship between Fe addition and the elastic–plastic properties of titanium alloys. The slip systems’ activity during the deformation process was also discussed using the Schmid factor. It shows that Fe addition is beneficial for the activity of prismatic and pyramidal slip systems, especially in the {10$\overline{1}$0} , {10$\overline{1}$1} , and {11$\overline{2}$2} slip systems.

A novel type of titanium matrix composite (TMC) with a uniform network microstructure has been successfully fabricated by adjusting particle-size mismatch (Φ). This study can also improve the understanding of the effects of particle size on microstructure and mechanical properties, particularly in titanium matrix composites reinforced with graphite flakes (GNFs). Microstructural analysis reveals the absence of noticeable defects, and significant grain refinements have been realized. The experimental results indicate that the yield strength of the mismatched composite is improved by 24.75% compared to that of normal composites. The micro-hardness also exhibits a 10.3% increase. These enhancements can be attributed to the introduction of particle-size mismatch, the refinement of the microstructure, and the deflection of interface cracks. The presence of distorted GNF lattices in the interface micro-region of the composites primarily results from the appropriate sizing of different particles.

Al-Li alloys present significant challenges for conventional fusion-based additive manufacturing (AM) due to their low evaporation temperature and high reactivity with oxygen. As a solid-state process, friction stir additive manufacturing (FSAM) is expected to eliminate melting and solidification during processing, thereby overcoming these limitations. This study investigates the FSAM of 2195 Al-Li alloy through temperature measurements and numerical simulations. The research focuses on the temperature at the center of the deposited region and the phase evolution before and after FSAM. The results indicate that during FSAM, the temperature at the center of the deposited zone ranges from 458 to 497 °C. In terms of phase constitution, the T3-tempered alloy primarily consists of an α-Al matrix and the δ’ (Al₃Li) phase. The T8-tempered alloy contains α-Al, θ’ (Al₂Cu), and T₁ (Al₂CuLi) phases. In the nugget zone (NZ), the peak temperature exceeds 450 °C. As a result, the T₁ and θ’ phases dissolve, leaving only a small amount of δ’/β’ precipitates. This study presents a preliminary investigation based on a single-layer FSAM process. These findings provide a foundation for optimizing FSAM process parameters for Al-Li alloys.

FeNiCrMo austenitic stainless steel has good corrosion resistance but a low surface hardness, which limits its wear resistance under high load. FeNiCrMo, FeNiCrMo with 10 wt.% tungsten carbide (WC) (45–106 μm) and FeNiCrMo with 10 wt.% WC-17Co (15–45 μm) were deposited by laser cladding at 1200 W and 480 mm/min, and their phase composition, microstructure, microhardness, wear behaviour and corrosion resistance were compared. Both particle additions promoted a columnar-to-equiaxed transition and the formation of W₂C. The coarse WC particles dissolved only partially and raised the hardness little, from 473 to 475 HV_0.2, while the finer WC-17Co particles dissolved more completely and raised it to 550–600 HV_0.2. On the worn surfaces, the ploughing grooves of the unreinforced coating were still present but shallower and narrower, indicating that abrasion was reduced in severity rather than replaced. The particles nevertheless impaired the corrosion resistance, most strongly for WC-17Co. FeNiCrMo/WC gave the best overall result. Its specific wear rate was the lowest of the three coatings, 0.73 × 10⁻⁶ mm³·N⁻¹·m⁻¹ at 90 N and roughly an order of magnitude below the unreinforced coating, and its mass loss was the smallest at every load, while its corrosion resistance fell far less than that of FeNiCrMo/WC-17Co, with an Ecorr of −0.393 V against −0.738 V. The coarse, only partly dissolved WC particles provide the most favourable combination of wear and corrosion resistance and are recommended for FeNiCrMo components operating under high load in only mildly aggressive conditions.