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Although poly-ether-ether-ketone (PEEK) implants hold significant medical promise, their bioinert nature presents challenges in osseointegration and bone ingrowth within clinical contexts. To mitigate these challenges, the present study introduces Diamond PEEK/bioactive glass (BG) composite scaffolds, characterized by macro/micro dual-porous structures, precisely fabricated via laser powder bed fusion (LPBF) technology. The findings indicate that an increase in BG content within these scaffolds significantly augments their hydrophilicity and hydroxyapatite formation capacities. Stress-strain curve analysis demonstrates reliable load-bearing stability across all scaffold types. In vitro assessments confirmed the non-cytotoxicity of PEEK/BG samples and demonstrated improved osteogenic differentiation and mineralization with increased BG incorporation. Further, in vivo experiments illustrated that the Diamond porous structure of these scaffolds facilitated bone growth, an effect notably amplified with higher BG content. Particularly in groups with 15 wt.% and 25 wt.% BG scaffolds, new bone formation was observed not only within the macropores of the Diamond structure but also within the micropores inside the scaffold rod, suggesting an almost seamless fusion with the new bone. This demonstrates the scaffolds' effective osteointegration and bone ingrowth properties. This study conclusively established the effectiveness of Diamond-structured PEEK/BG composite scaffolds, fabricated via LPBF, in bone repair. It highlights the crucial role of BG in enhancing osteogenic potential through interaction with the macro/micro pores of the scaffold. STATEMENT OF SIGNIFICANCE: This study addresses the bioinert nature of PEEK implants by developing Diamond-structured PEEK/bioactive glass (BG) composite scaffolds by laser powder bed fusion. The dual-porous macro/microstructure enhances hydrophilicity and hydroxyapatite formation, vital for bone regeneration. By adjusting the BG content, we controlled the melt viscosity and sintering rate, leading to the formation of beneficial microscale pores. These pores resolve the issue of ineffective bioactive fillers in previous LPBF-fabricated scaffolds, enhancing the osteogenic potential of BG and inducing superior bone ingrowth and osseointegration. In vitro and in vivo analyses show enhanced osteogenic differentiation, mineralization, and bone growth, underscoring the clinical potential of these scaffolds for bone repair., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Schwartz diamond graded porous structures (SDGPSs), constructed by a triply-periodic-minimal-surface diamond unit cell topology, were developed with various unit cell sizes and printed by laser powder bed fusion (LPBF) from a commercially pure titanium powder for bone implant applications. The effect of unit cell size on the printability, strut dimensions, stress and strain distributions, mechanical properties and energy absorption capability of SDGPSs was investigated. The results indicate the good printability of SDGPSs via LPBF with multiple unit cell sizes from 3.5 mm to 5.5 mm through the three-dimensional reconstruction from micro-computed tomography. The unit cell size plays a critical role in both strut diameters and specific surface areas of SDGPSs. An increase in the unit cell size leads to a reduction in the experimental Young's modulus from 673.08 MPa to 518.71 MPa and compressive yield strength from 11.43 MPa to 7.73 MPa. The mechanical properties of LPBF-printed SDGPSs are higher than those predicted by the finite element method, which is attributed to the higher volume fractions of the printed SDGPSs than the designed values. Furthermore, a rise in unit cell size leads to the decrease of energy absorption capability from 6.06 MJ/mm 3 to 4.32 MJ/mm 3 and exhibits little influence on the absorption efficiency. These findings provide a good understanding and guidance to the optimization on the unit cell size of functionally graded porous structures for desirable properties., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Ti-6Al-4V Gyroid triply periodic minimal surface (TPMS) lattices were manufactured by selective laser melting (SLM). The as-built Ti-6Al-4V lattices exhibit an out-of-equilibrium microstructure with very fine α' martensitic laths. When subjected to the heat treatment of 1050°C for 4h followed by furnace cooling, the lattices show a homogenous and equilibrium lamellar α+β microstructure with less dislocation and crystallographic defects compared with the as-built α' martensite. The as-built lattices present very rough strut surfaces bonded with plenty of partially melted metal particles. The sand blasting nearly removed all the bonded metal particles, but created many tiny cracks. The HCl etching eliminated these tiny cracks, and subsequent NaOH etching resulted in many small and shallow micro-pits and develops a sodium titanate hydrogel layer on the surfaces of the lattices. When soaked in simulated body fluid (SBF), the Ti-6Al-4V TPMS lattices were covered with a compact and homogeneous biomimetic hydroxyapatite (HA) layer. This work proposes a new method for making Ti-6Al-4V TPMS lattices with a homogenous and equilibrium microstructure and biomimetic HA coating, which show both tough and bioactive characteristics and can be promising materials usable as bone substitutes., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Triply periodic minimal surface (TPMS) structures have already been shown to be a versatile source of biomorphic scaffold designs. Therefore, in this work, Ti-6Al-4V Gyroid and Diamond TPMS lattices having an interconnected high porosity of 80-95% and pore sizes in the range of 560-1600 μm and 480-1450 μm respectively were manufactured by selective laser melting (SLM) for bone implants. The manufacturability, microstructure and mechanical properties of the Ti-6Al-4V TPMS lattices were evaluated. Comparison between 3D micro-CT reconstructed models and original CAD models of the Ti-6Al-4V TPMS lattices shows excellent reproduction of the designs. The as-built Ti-6Al-4V struts exhibit the microstructure of columnar grains filled with very fine and orthogonally oriented α' martensitic laths with the width of 100-300 nm and have the microhardness of 4.01 ± 0.34 GPa. After heat treatment at 680°C for 4h, the α' martensite was converted to a mixture of α and β, in which the α phase being the dominant fraction is present as fine laths with the width of 500-800 nm and separated by a small amount of narrow, interphase regions of dark β phase. Also, the microhardness is decreased to 3.71 ± 0.35 GPa due to the coarsening of the microstructure. The 80-95% porosity TPMS lattices exhibit a comparable porosity with trabecular bone, and the modulus is in the range of 0.12-1.25 GPa and thus can be adjusted to the modulus of trabecular bone. At the same range of porosity of 5-10%, the moduli of cortical bone and of the Ti-6Al-4V TPMS lattices are in a similar range. Therefore, the modulus and porosity of Ti-6Al-4V TPMS lattices can be tailored to the levels of human bones and thus reduce or avoid "stress shielding" and increase longevity of implants. Due to the biomorphic designs, and high interconnected porosity and stiffness comparable to human bones, SLM-made Ti-6Al-4V TPMS lattices can be a promising material for load bearing bone implants., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Laser powder bed fusion (L-PBF) involves the coupling of multiple physical fields at different scales. Capturing the dynamic flow and thermal behavior of the melt pool during the L-PBF process through experimentation and predicting its quality is challenging, thus numerical simulation becomes a valuable method. The simulation results enable the prediction and assessment of the impact of material and process parameter changes on the quality of the final product. This paper reviews the methods for selecting appropriate models, performing simulation calculations, and analyzing the results. This paper makes several noteworthy contributions. It provides a comprehensive summary of the physical model, heat loss model, required heat source for simulations, and stresses generated within the melt pool. Furthermore, it explores the practical applications of L-PBF melt pool simulations, especially in defect analysis and the fabrication of complex structures. Finally, it concludes with an insightful analysis of the current trends in L-PBF simulations and outlines potential research directions to advance the development of melt pool simulations. [ABSTRACT FROM AUTHOR]

A numerical approach to model the selective laser sintering (SLS) of polypropylene is proposed. A 3D thermal model was developed and thus enables the prediction of the temperature fields and the extension of the sintered area in the powder bed taking into account the phase change during multiple laser passes. Powder-liquid, liquid-solid and solid-liquid phase changes were modelled during the SLS and the subsequent cooling processes. Then, a 3D thermomechanically coupled model was set up based on the temperature results of the thermal model in order to predict the distortion of the produced parts after cooling down. Different pre-heating temperatures were considered, highlighting their influence on the final part properties. [ABSTRACT FROM AUTHOR]

Ni–Ti alloys based on triple-periodic minimal surface lattice metamaterials have great application potential. In this work, the triply periodic minimal surface (TPMS) lattice structures with the same volume fraction from a normal Gyroid lattice to an octuple interlacing Gyroid lattice were prepared by the laser powder bed fusion (LPBF) technique. The influence of the interlacing-cell number on manufacturability, uniaxial compression mechanical behaviors, and hyperelastic responses of Ni–Ti lattice structures are analysed by experiments. The stress distributions and fracture mechanism of multicell interlacing lattice structures are illustrated by the finite element method. The obtained results reveal that when the volume fraction is the same, the specific surface area of the lattice structure increases with increasing interlacing-cell number, and the curvature radius of the single-cell strut reduces, which leads to the decrease in the manufacturability of the lattice structure. Meanwhile, the diameter of the single cell strut decreases, and the stress it can bear decreases, which leads to a decline in the compressive mechanical property of the lattice structure. However, the number of struts increases with the increase of interlacing cells, which makes the stress distribution of the lattice structure more uniform. The cyclic compression results indicate that with increasing interlacing-cell number, the proportion of the hyperelastic recoverable strain increases, and the residual strain in the cyclic compression test decreases. For the lattice structure with a chiral arrangement of single cells, the manufacturability, compressive mechanical properties, and hyperelasticity are comparable to those with a normal arrangement. Notably, the Ni–Ti Gyroid TPMS lattice structures have superior hyperelasticity properties (98.87–99.46 % recoverable strain). [Display omitted] •Multi-cell interlacing Gyroid TPMS structures were designed and made via LPBF. •Manufacturing deviations among different multicell lattices were illustrated. •Stress concentration can be relieved by multi-cell interlacing design. • Multiple designs can reduce structural stiffness and enhance hyperelasticity. • The mechanical properties of chiral and normal structures are comparable. [ABSTRACT FROM AUTHOR]

[Display omitted] • The SiC/Al composites was fabricated by LPBF combined with VPI. • The particle size distribution significantly affect the properties of the SiC/Al composites. • The pre-oxidation is beneficial for preventing the lamellar cracking. • The experimental data were in good agreement with the predicted values based on Kerner's model. A novel method has been developed to fabricate SiC/Al composites by the combination of laser powder bed fusion (LPBF) and vacuum-pressure infiltration. The effects of the SiC particle size distribution and pre-oxidation on the microstructure and properties of SiC/Al composites were investigated. A new phenomenon of severe lamellar cracking was observed in SiC/Al composites without pre-oxidation treatment, which can be explained in terms of the mechanism of interlayer bonding. The results showed that the residual porosity of the sample without pre-oxidation treatment s was higher than 3 %, with a maximum of (8.16±0.57) %, which was much higher than that of the pre-oxidised samples(1 % – 2%). The bulk density of the powders was significantly improved by designing the material system with mono-, bi-, and tri-modal particle size distributions and the density of final SiC/Al samples gradually increases from 2.804±0.009 to 2.871±0.008 g/cm3, and the volume fraction of SiC increases from 36.7 vol% to 50.1 vol%. As a result, the coefficients of thermal expansion (CTE) of SiC/Al composites varies consistently with the volume fraction of SiC, decreasing from 13.72 to 10.84×10−6 °C−1. Our study shows that this method has the potential for great applications. [ABSTRACT FROM AUTHOR]

Poly-ether-ether-ketone (PEEK) implants fabricated by laser powder bed fusion (LPBF) are promising candidates for bone tissue engineering because of the excellent biocompatibility of the material and the ability to realize personalized bone repair. However, the weak LPBF processability and biological inertness of PEEK limit the clinical application. In this work, bioactive glass (BG) is blended into PEEK and found to improve the LPBF processability and bioactivity. The results show that PEEK/BG composite powders exhibit better LPBF processability due to the wider sintering window (48.9%–79.1% wider) and higher thermal conductivity (5.7%–23.0% higher) compared with the pure PEEK as well as the crystallization inhibition during the cold powder spreading. The melting enthalpy and thermal stability of the composite reduce when the BG content increases, thereby leading to the decrease of the optimal laser power during the LPBF process. The modulus of PEEK/BG composites ranges from 2685.82 MPa to 3729.33 MPa, which can match the modulus of human cancellous bone. The variation of lattice constant c and cell volume with the laser power of the composites all show a similar trend to the mechanical properties. BG can promote hydroxy-carbonate-apatite deposition, suggesting that BG has great potential to promote osteogenesis. By varying the amount of BG incorporated, the PEEK composite implants can be applied to different regions in the body depending on the specific clinical requirements. [Display omitted] [ABSTRACT FROM AUTHOR]

• The interrelationships among process parameters, microstructure and macroscopic properties are established. • Effect of element evaporation on microstructure and transformation behavior is presented. • Effect of the thermal effect during SLM process on martensite formation is revealed. Cu-based shape memory alloys are promising materials for functional or intelligent applications because of its good shape memory properties and low cost. As an additive manufacturing technique, selective laser melting (SLM) is easy to produce such complex intelligent components, moreover, the rapid solidification rate can obtain fine microstructure and get good properties. In this study, CuZnAl shape memory alloys were prepared by SLM for the first time to study the effect of the process parameters on the relative density, phase constitution, microstructure, phase transformation behavior, microhardness and superelastic response. Results show that the intrinsic reason for the differences in the microstructure and the macroscopic properties is the different Zn content in samples fabricated with different energy densities. The lower energy densities lead to the lower amount of Zn evaporation and thus the higher remained Zn content in the fabricated samples. In terms of phase constitution, samples with higher Zn content mainly consist of martensite (β') and present needle-like shape microstructure morphology. On the contrary, samples with lower Zn content are predominated by α phase and have rod-like or even equiaxed shape microstructure. In addition, higher amount of martensite in the samples results in the higher peak intensity in the DSC curves, the higher microhardness and the lower irrecoverable strain. [ABSTRACT FROM AUTHOR]

Abstract Silver, as a precious metal, is widely used in the consumer goods industry and high-tech fields. Selective Laser Melting (SLM), as an Additive Manufacturing (AM) technique, has the potential to make complex structural components of Ag alloy but is often limited by the high reflectivity and thermal conductivity of Ag. This study seeks to determine the optimum solution to this limitation by identifying the most suitable laser device, material and parameters for manufacturing Ag alloy through SLM. The effects of laser power, scanning speed and scanning strategy on the morphology, microstructure, density and mechanical properties of Ag alloy are described. It reveals that the density and Vickers hardness of Ag alloy are largely determined by the molten pool size, grain size, residual stress and cooling rate. Results of experiments and theoretical calculations further reveal that the heterogeneity and anisotropy formation of microstructure and defects are related to variations in the cooling rate and thermal gradient caused by the laser scanning strategy. The high scanning speed of the laser and high thermal conductivity of the Ag lead to higher cooling rates, thereby enabling SLM processed Ag alloy to have a density as high as 96.7% and hardness of up to 148.9HV. Graphic abstract Unlabelled Image Highlights • Selective laser melting can increase hardness by up to 200% by improving grain refinement and increasing residual stress. • High reflectivity and thermal conductivity can be addressed by optimized laser devices with high power and short wavelengths. • Homogeneous components can be obtained by placing laser scanning tracks of uniform length parallel to the XY axles. [ABSTRACT FROM AUTHOR]