Fusion Properties Research Articles

Exploring ash fusion characteristics and thermal decomposition of biomass through thermogravimetric analysis

This study aims to investigate the ash fusion properties along with thermogravimetric examination of different biomass in an inert atmosphere at 20, and 30 °C/min. According to the accepted procedures, the physicochemical characterizations of biomass Sawdust, Soybean (Glycine max) as well as Eucalyptus (Eucalyptus globulus) were completed. Thermodynamic and kinetic parameters were determined within the active pyrolysis zone using iso-conversional models like FWO and KAS techniques. During thermal deterioration, biomass loses mass through moisture loss, passive and active pyrolysis. The active pyrolysis zone was responsible for 50–55% of the mass loss between 180 and 395 °C. The activation energy values were 175.08and 174.21 kJ/mol based on KAS and FWO models, respectively, for sawdust; 153.15 and 151.47 kJ/mol for soybean and for eucalyptus 168.70 and 167.70 kJ/mol, respectively. The ash fusion behaviours of biomass showing 1506 °C deformation temperature for soybean followed by 1465 °C for eucalyptus and 1289 °C for sawdust and their variation processes under decreasing atmosphere were examined to reduce ash-related problems during gasification.

Influence of heat treatment on microstructure and magnetic properties of laser powder bed fusion generated NdFeB magnets

Influence of heat treatment on microstructure and magnetic properties of laser powder bed fusion generated NdFeB magnets

Quantitative relationships between elastic modulus of rod and biomechanical properties of transforaminal lumbar interbody fusion: a finite element analysis.

Currently, some novel rods with lower elastic modulus have the potential as alternatives to traditional titanium alloy rods in lumbar fusion. However, how the elastic modulus of the rod (rod-E) influences the biomechanical performance of lumbar interbody fusion remains unclear. This study aimed to explore the quantitative relationships between rod-E and the biomechanical performance of transforaminal lumbar interbody fusion (TLIF). The intact finite element model of L1-S1 was constructed and validated. Then 12 TLIF models with rods of different elastic moduli (ranging from 1GPa to 110GPa with an interval of 10GPa) were developed. The range of motion (ROM) of the fixed segment, mean strain of the bone graft, and maximum von Mises stresses on the cage, endplate, and posterior fixation system models were calculated. Finally, regression analysis was performed to establish functional relationships between rod-E and these indexes. Increasing rod-E decreased ROM of the fixed segment, mean strain of the bone grafts, and peak stresses on the cage and endplate, while increasing peak stress on the screw-rod system. When rod-E increased from 1GPa to 10GPa, ROM decreased by 10.4%-39.4%. Further increasing rod-E from 10GPa to 110GPa resulted in a 9.3%-17.4% reduction in ROM. The peak stresses on the posterior fixation system showed a nonlinear increase as the rod-E increased from 1GPa to 110GPa under most loading conditions. The R 2 values for all fitting curves ranged from 0.76 to 1.00. The functional relationships between rod-E and the biomechanical properties of TLIF were constructed comprehensively. When the rod-E exceeds 10GPa, further increases may not significantly improve stability, however, it may increase the risk of fixation failure. Therefore, a rod with an elastic modulus of approximately 10GPa may provide optimal biomechanical properties for TLIF.

Spectrum and carcinogenic properties of thyroglobulin gene fusions in thyroid.

Approximately 10-20% of thyroid cancers are driven by gene fusions, which activate oncogenic signaling through aberrant overexpression, ligand-independent dimerization, or loss of inhibitory motifs. We identified 13 thyroid tumors with thyroglobulin (TG) gene fusions and aimed to assess their histopathology and the fusions' oncogenic and tumorigenic properties. Of 11 cases with surgical pathology, 82% were carcinomas and 18% noninvasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTP). TG fusions preserved exon(s) 1, 1-15, 1-35 or, most frequently, 1-47 of TG and, based on the 3' partner were grouped as (i) involving receptor tyrosine kinases (RTKs) (TG::FGFR1, TG::RET, TG::ALK, TG::NTRK1), (ii) driving aberrant DPRX and chromosome 19 microRNA cluster expression (TG::DPRX), or (iii) involving IGF2 mRNA-binding protein (TG::IGF2BP1). All 13 fusion-positive tumors exhibited strong (8.5±3.3 log2-fold) 3' partner overexpression driven by the TG promoter. Gene expression analysis revealed TG::RET- and TG::ALK-positive tumors being BRAFV600E-like and remaining tumors RAS-like. In thyroid PCCL3 cells, the TG::NTRK1 fusion demonstrated both spontaneous and ligand-associated dimerization, activated downstream MAPK, AKT, and STAT3 signaling, and drove xenograft tumorigenesis in nude mice. FDA-approved NTRK inhibitors entrectinib and larotrectinib effectively blocked TG::NTRK1 signaling in vitro and inhibited xenograft tumor growth in vivo. In summary, we report a spectrum of TG gene fusions as recurrent oncogenic events in thyroid cancer and NIFTP that drive strong overexpression of partner genes, frequently RTKs. The TG::NTRK1 fusion is prone to dimerization, activates oncogenic signaling, drives tumorigenesis in thyroid cells, and, like other fusions involving RTKs, represents a potential therapeutic target in thyroid cancer.

Influence of the graphene incorporation on nanostructure and thermal properties of the laser powder bed fusion processed AlSi12 matrix composites

The successful fabrication and implementation of graphene-reinforced aluminum (Al) matrix composites (AMCs) have been obstructed by the undesirable graphene-Al reactions during their casting or inability of complex part manufacturing through powder metallurgy techniques. The emergence of the laser powder bed fusion (L-PBF) process with extremely short melt duration and almost no limitations in terms of the manufacturing of intricate features has renewed the interests for fabrication of graphene-reinforced AMCs. In this study, the influence of graphene incorporation into AlSi12 on L-PBF processability and defect formation is studied. The specific heat capacity, coefficient of thermal expansion, thermal diffusivity and thermal conductivity of composites were compared to those of the monolithic AlSi12 alloy. Microstructure-thermal properties relationship was studied through transmission electron microscopy (TEM), high-resolution TEM (HRTEM), electron backscatter diffraction (EBSD), electron dispersive spectroscopy (EDS) and Raman spectroscopy. This study provides valuable insights into (i) the chance of survival of graphene, (ii) possibility of graphene changing into other forms of carbon, and (iii) graphene-Al reactions during the L-PBF process. It was found that most of the graphene/graphite particles transformed into Al4C3. Among the survived carbon material, it appears they are more disordered than the initial graphene/graphite, though highly ordered ones with almost no defects were also detected. Thermal expansion measurements showed that the coefficient of thermal expansion decreased from 27.5×10-6/˚C for AlSi12 to 25.3×10-6/˚C for AlSi12-0.25Gr and 25.5×10-6/˚C for AlSi12-0.5Gr. Regarding thermal conductivity, in the case of AlSi12-0.5Gr, it either matched or was lower than that of pure AlSi12 within the tested temperature range. In contrast, AlSi12-0.25Gr exhibited higher thermal conductivity than AlSi12 in the temperature range of 150-350 ˚C.

In Vitro Assessment of the Extended 21-Day Microbial Barrier Provided by the Exofin Fusion Surgical Incision Closure System.

Background: Tissue adhesives are increasingly being used as alternatives to traditional sutures and staples in surgical incision closure applications. Exofin Fusion, a novel cyanoacrylate-based adhesive with a mesh, has been developed to enhance surgical incision closure. This study investigates the microbial barrier effectiveness of Exofin Fusion. Methods: An in vitro assessment of 35 plates, including challenge organisms, negative controls, and positive controls, was conducted by an independent research organization, North American Science Associates, Inc (NAMSA), USA. Exofin Fusion was applied to the plates aseptically. Each plate was then inoculated with specific challenge organisms. Observations for visible growth or color changes in the media were made over a 21-day period. Results: The results demonstrated no growth or color changes on test plates for common pathogens such as Staphylococcus aureus, Staphylococcus epidermidis, Methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Aspergillus brasiliensis throughout the 21-day period. Candida albicans showed no growth or color changes up to day 20; however, two out of five replicates exhibited growth on day 21. Conclusions: The study confirms the microbial barrier properties of Exofin Fusion, as it effectively prevents the penetration of challenge organisms for the entire test period. Despite the growth of C. albicans in two replicates on day 21, the adhesive demonstrates remarkable efficacy in protecting against microbial infiltration. These findings suggest the potential clinical utility of Exofin Fusion in surgical incision closure applications, highlighting its significance in healthcare settings.

Characterization and Optimization of Mechanical Properties in Laser Powder Bed Fusion Manufactured 316L Stainless Steel

This study investigates the mechanical properties and microstructure of 316L stainless steel fabricated using laser powder bed fusion (PBF-LB) additive manufacturing with different layer thick nesses and orientations. Impact toughness is evaluated under various conditions as well as bending fatigue performance to understand the influence of layer thickness and surface quality on fatigue lim its. Microstructural analysis using scanning electron microscopy (SEM) provides insights into grain structure. Key findings include the superior impact toughness of the vertical orientation, particularly notable in specimens with a layer thickness of 40 µm. Bending fatigue tests revealed distinctive behav ior influenced by layer thickness and surface quality, with the 80 µm thickness and vertical orientation demonstrating lower fatigue limits. These insights contribute to optimizing manufacturing processes and enhancing material suitability for diverse applications.

Directly Fused Porphyrin-Tetracyanopentacenequinone Conjugates: Role of the Cross-Conjugated, Powerful Electron Acceptor in Promoting Highly Efficient Charge Separation.

Tetracyanopentacenequinone, a powerful electron acceptor, is fused directly to the porphyrin π-system to create a new class of donor-acceptor conjugates. Owing to the direct fusion and electron-deficient property of tetracyanopentacenequinone, strong intramolecular charge transfer both in the ground and excited states was witnessed. As a control, porphyrin fused with pentacenequinone was also investigated. Upon complete spectral and electrochemical characterization, the excited state properties were initially probed by time-dependent DFT studies, and the occurrence of electron transfer from different excited states was established. Free-energy calculations revealed higher exothermic electron transfer (> 600 mV) than the control pentacenequinone-porphyrin systems. Pump-probe studies covering broad spatial and temporal regions revealed efficient excited state charge separation. This was unlike the control pentacenequinone-porphyrin system, where slow charge separation was witnessed only in the case of the zinc derivatives but not the free-base ones. The lifetimes of the charge-separated states ranged between 30-500 ps depending on the solvent and metal ion in the porphyrin cavity. The significance of cross-conjugated tetracyanopentacenequinone fused directly to the porphyrin π system in promoting highly exothermic and efficient charge separation, irrespective of its cross conjugation, is borne out from this study.

A novel data fusion method to leverage passively-collected mobility data in generating spatially-heterogeneous synthetic population

Conventional methods to synthesize population use household travel survey (HTS) data. They generate many infeasible attribute values due to sequentially generating sociodemographics and spatial attributes and encounter a low spatial heterogeneity issue due to a low sampling rate of the HTS data. Passively collected mobility (PCM) data (e.g., cellular traces) provides extensive spatial coverage but poses integration challenges with HTS data due to differences in spatial resolution and attributes. This study introduces a novel cluster-based data fusion method to address these limitations and simultaneously generate synthetic populations with accurate sociodemographics and home–work locations at high spatial heterogeneity. Spatial clustering is adopted to align the spatial resolution of HTS and PCM data, facilitating effective data integration. The data fusion process is reformulated into cluster-specific low-dimensional optimization subproblems to ensure computational tractability. Analytical properties are derived to retain essential distributional characteristics from both datasets in the fused distribution. The spatial clustering process is optimized to ensure such distributional consistencies while maintaining a balance between feasibility and heterogeneity of the synthetic population. The data fusion properties are validated using HTS and LTE/5G cellular signaling data from Seoul, South Korea. Validation against census data confirms the method’s efficacy in maintaining distributional consistency while increasing spatial heterogeneity, with 97% of the generated population being unobserved in the HTS data. This research advances methods to synthesize a population by leveraging the complementary strengths of HTS and PCM data, providing a robust framework for generating spatially diverse synthetic populations essential for urban planning.

Effect of Surface Finish and Temperature on Low Cycle Fatigue Behavior of GRCop‐42

ABSTRACTThis study investigates the impact of various surface finishes on the low cycle fatigue (LCF) properties of laser powder bed fusion GRCop‐42. The evaluated surfaces include as‐built, machined, and chemically polished finishes (1.0% and 2.0% ranges). LCF life of polished GRCop‐42 was assessed at cryogenic (−195°C), ambient, and elevated temperatures (200°C, 400°C, 600°C, and 800°C) across three strain ranges. Results indicate that surface finish has minimal impact on LCF life. Stress across different strain levels showed minimal effect of surface finish on cyclic hardening/softening. Cryogenic temperatures led to cyclic hardening followed by stabilization, while ambient and 200°C temperatures showed initial hardening followed by softening. At 400°C and above, specimens displayed continuous cyclic softening. Fractography showed that surface finish impacts plastic deformation: as‐printed and polished surfaces had brittle fractures, while machined specimens were ductile. Specimens at cryogenic and ambient temperatures exhibited brittle fractures, whereas those at elevated temperatures showed plastic deformation and microcracks.

Mechanical properties of laser powder bed fusion processed Inconel alloy IN718 in different heat treatment conditions through small scale specimen testing

In this study, IN-718 samples were printed using laser powder bed fusion (LPBF) process to investigate the effect of printing parameters (in terms of Volume Energy Density, (VED)), printing orientation, heat treatment and test temperature on the microstructure and mechanical properties. Tensile properties were evaluated using small-scale tensile specimens extracted from samples printed with 15 different processing parameters (by varying scan speed and scan power) in two print orientations (XY and XZ plane), in three microstructural conditions (as-printed (AP), printed + solution treated and aged (STA), printed + hot isostatically pressed (HIP) + STA), at two different temperatures (room temperature and 650 °C). The mechanical properties obtained from testing of small-scale tensile specimens were compared with results obtained from testing of specimens following ASTM E8 standard, to understand effect of specimen size on mechanical properties. Based on microstructural analysis, it was observed that below a VED value of 50 J/mm3, the conduction region prevailed, with the presence of irregular lack of fusion porosities. In VED range of 50–100 J/mm3, the transition prevailed with highly dense samples (over 99 % of theoretical density) with minimal porosity. Above a VED of 100 J/mm3, the keyhole regime prevailed with the presence of spherical keyhole porosities. STA heat treatment improved YS and UTS to ∼1200 and ∼1400 MPa, respectively, while reducing ductility to ∼15 %. HIP + STA had similar effect on tensile properties as STA heat treatment. Based on tensile strength data, it was observed that HIP is not essential for parts printed with optimum parameters. Sample size in the present study was found to have an insignificant effect on tensile properties. In conclusion, the study provides an insight into the role played by printing parameters, printing orientation, and post-processing on defects, microstructures and thereby on the mechanical properties.

Optimization of waste biomass demineralization through response surface methodology and enhancement of thermochemical and fusion properties

This study examines the impact of leaching with dilute hydrochloric acid solution on the reduction of ash content and the thermal degradation behavior of sugarcane bagasse. Response surface methodology (RSM) was used to statistically design the experiments and investigate the effect of three independent variables: treatment time, solid-to-liquid ratio, and reagent concentration. The leaching conditions were further optimized and experimentally validated for maximum ash reduction for suitability of treated biomass as feedstock for thermochemical conversion technologies. Reagent concentration and treatment time directly affected ash reduction, while the solid-to-liquid ratio inversely influenced it. Concentration had the highest impact, and treatment duration had the least. The maximum 78.2% ash reduction was achieved by treating the biomass with 1 M HCl for 80 min at a solid-to-liquid ratio of 50:1 (wt/vol). This ash reduction also resulted in a 9.82% increase in higher heating value (HHV). Hemicellulose hydrolysis during leaching was observed through chemical composition and Fourier-transform infrared spectroscopy (FTIR). Ash fusion temperatures increased, indicating more thermally stable biomass. Thermogravimetric analysis (TGA) showed elevated maximum degradation temperature and activation energy.

Microstructure and mechanical properties of laser powder bed fusion Ti-6Al-4V after HIP treatments with varied temperatures and cooling rates

This work investigated non-standard HIP cycles for PBF-L Ti-6Al-4V and characterized microstructure and tensile properties to compare between material that originated from the same build. For 920°C, faster cooling rates (100°C/min, 2000°C/min) were found to promote bi-lamellar α microstructure, while the 2000°C/min cooling rate improved the strength. For HIP with lower temperature (800°C, 200 MPa), coarsening was minimized resulting in strength improvement. The slow cooling rate (12°C/min) showed the highest strength as faster rates increased the amount of orthorhombic martensite (α″). For HIP with higher temperature (1050°C), the as-built crystallographic texture was reduced and equiaxed prior-β grain morphology resulted, leading to more isotropic tensile properties. However, the cooling rate (2000°C/min) was not enough to prevent formation of grain boundary α, which reduced strength and elongation. Machine learning was carried out on the dataset via Principal Component Analysis (PCA) to reduce the dimensionality of the parameters and microstructural features.

Influence of annealing on microstructures and mechanical properties of laser powder bed fusion and wire arc directed energy deposition additively manufactured 316L

The annealing response of 316L stainless steel manufactured with both laser powder bed fusion (PBF-LB) and wire-arc directed energy deposition (DED-Arc) was investigated in the context of microstructural evolution and mechanical properties. Because additive manufacturing (AM) comprises several technologies that differ in heat source, feedstock, and scan strategy, among other build variables, the final products can experience a range of thermal histories and defect (dislocation) populations. These unique thermal histories can subsequently influence as-built properties and annealing response of AM materials, most notably those manufactured with different AM deposition processes. The PBF-LB process (with higher cooling rates) yielded finer austenite microstructures having more lattice strain, higher dislocation densities, and higher yield strength values than the DED-Arc 316L process (with lower cooling rates). Electron backscattered diffraction (EBSD) data of the kernel average misorientation (KAM), boundary density, and geometrically necessary dislocation (GND) density support the differences in lattice strain. As a result, the PBF-LB 316L exhibited more recovery and recrystallization after annealing at elevated temperatures above 873 K based on changes to yield strength, work hardening behavior, and microstructure evolution. The DED-Arc 316L exhibited a δ-ferrite/austenite microstructure with microsegregation that influenced deformation mechanisms active after annealing. Tensile data, deformed microstructures and misorientation histograms from EBSD showed a decreasing amount of deformation twinning when comparing the as-built condition to annealed conditions (up to 1473 K/1h) of PBF-LB 316L. The opposite trend was noted in DED-Arc 316L. The behavior was interpreted to be due to the differences in chemical segregation during solidification and the effects of heat treatment on chemical homogenization and local stacking fault energy.

On the effect of energy input on microstructure evolution and mechanical properties of laser beam powder bed fusion processed Ti-27Nb-6Ta biomedical alloy

Additive manufacturing of pre-alloyed Ti-27Nb-6Ta powder by laser beam powder bed fusion (PBF-LB/M) employing a wide range of processing parameters is reported. An in-depth microstructure analysis along the whole process chain from powder feedstock material to additively manufactured bulk structures was conducted employing scanning electron microscopy (SEM) as well as X-ray and high-energy synchrotron diffraction. It is shown that near-fully dense parts (≥99.96 %) with β+α’’ dual-phase microstructure and very homogenous element distribution are obtained in a large process window. In particular, a considerable influence of the energy input during PBF-LB/M on the solidification microstructure, i.e. phase composition and texture, is found. With increasing energy per unit area (EA) both an increase in the volume fraction of the bcc β-phase and more pronounced texture components are seen. Furthermore, the mechanical behavior was evaluated under monotonic tensile loading. The PBF-LB/M processed Ti-27Nb-6Ta structures feature good mechanical properties with ultimate tensile strength (UTS) and strain to failure values of up to 768 MPa and 33.8 %, respectively. Due to the strong impact of the energy input during additive manufacturing on the microstructure evolution, however, an inverse strength-ductility behavior is observed. While UTS clearly decreases with increasing EA values, strain to failure increases at the same time. The underlying relationships between processing (energy input), microstructure and mechanical properties are explored and rationalized.

A Scan Strategy Based Compensation of Cumulative Heating Effects in Electron Beam Powder Bed Fusion

AbstractThe fabrication of complex geometries with uniform material properties in electron beam powder bed fusion (PBF-EB) remains a major challenge. Local material properties in PBF-EB are determined by the local thermal conditions and the spatio-temporal melt pool evolution. The local thermal conditions are governed by the cumulative heating effect on the hatch scale, which results from the superposition of temperature fields from adjacent hatch lines. The build-up of the cumulative heating effect at the beginning of a new hatch segment, without prior hatch lines, which results in regions with underdeveloped thermal conditions, is so far only rarely considered in the design of process strategies. This study introduces a numerical optimization scheme with the objective to minimize the extent of regions with underdeveloped thermal conditions at the beginning of line-based hatches, by means of scan strategy modifications. For this purpose, a simplified thermal solution is combined with an optimization approach to determine an optimal process strategy for line-based PBF-EB of a cuboid model geometry through the adaptation of individual hatch line spacing. Based on the approach determined for the model geometry, a generalized process strategy is derived for complex geometries and is numerically validated for different process parameter and geometry combinations.

Enhancement of the compressive performances of additive manufactured Corrax maraging stainless steel lattice by heat treatment

The objective of this study was to investigate the influences of integrated solution and aging treatment (SAT) on the compressive properties of laser powder bed fusion (LPBF) Corrax maraging stainless steel lattices. Cubic and face-centered cubic with Z-axis strut (FCCZ) lattices were produced and used to formulate two types of functionally-graded material (FGM) lattices. The lattices with FGM directions parallel and vertical to the stress were designated as FGM-P and FGM-V lattices, respectively. The compressive performances and fracture mechanisms were identified experimentally by digital image correction and theoretically by finite element analysis.The results show that SAT can significantly increase the specific strengths of these lattices by 34–42 %. The compressive performances and fracture mode of the FGM-V sample principally corresponded to the rule of mixture. However, the FGM-P sample did not follow the rule of mixture because its deformation concentrated only in the cubic-dominated regions. Moreover, the SEAs of the cubic and FGM-P samples were respectively improved by 30 % and 19 % by SAT, given their higher compressive strength and stable stress–strain curve. SAT can be applied to further extend the future application of these materials as cost-effective, high-performance lightweight structural materials.

Anisotropic microstructure and tensile property of laser powder bed fusion fabricated Al–Mn–Mg–Sc–Zr alloy built at different layer thickness

Laser powder bed fusion (LPBF) fabricated Al–Mn–Mg-Sc-Zr alloy generally possesses a bi-modal microstructure of columnar grains and equiaxed grains. Such an anisotropic microstructure would introduce varied tensile performance in different orientations. To date, few study on the microstructure and tensile property anisotropy have been reported for LPBF fabricated Al–Mn–Mg-Sc-Zr alloys built at different layer thicknesses, which limits the exploration in mechanical property optimization. In this work, the microstructure anisotropy and room-temperature tensile properties of LPBF produced and peak-aged Al–Mn–Mg-Sc-Zr alloys built at 30 and 60 μm layer thicknesses were systematically investigated by scanning electron microscope, transmission electron microscope, and tensile testing. A higher layer thickness of 60 μm resulted in coarser grains with the precipitates size remained similarly compared to the 30 μm specimens. This led to a reduced yield strength in 60 μm specimens (492–509 MPa) comparing to those in 30 μm specimens at 502 MPa–510 MPa. In addition, the existence of columnar grains within melt pools contributed to a larger effective slip length in the vertical direction than that in the horizontal orientation. Such difference in effective slip length in the loading direction contributed to a lower strength in vertical orientations. For ductility, the slightly higher defect level in 60 μm specimens (0.58%) resulted in reduced elongations of 3%–6% compared to those of 30 μm specimens (0.10%). The ductility anisotropy was attributed to the preferential distribution of gas pores and keyhole defects at melt pool boundaries.

Effect of powder properties, process parameters, and recoating speed on powder layer properties measured by in-situ laser profilometry and part properties in laser powder bed fusion

In laser-based powder bed fusion of metals (PBF-LB/M), the powder layer is the link between the powder properties and the resulting part quality. Powder layer quality is a key metric related to powder spreadability and ultimately part quality, yet it is still unclear how it can be quantified. This is due to the difficulty of studying powder layer properties during the process. This study investigates the influence of powder properties, process parameters, and recoating speed on the surface roughness of the powder layer and the part, as well as on the effective thickness of the powder layer and solidified layer, and the resulting relative part density. Utilizing in-situ laser profilometry, high-resolution topographical data of the powder layer and the part surface were acquired, with minimal interference to the PBF-LB/M process. Six AlSi10Mg powders with varying particle size distribution, morphology, and flowability were processed using a wide range of recoating speeds and scan speeds to create powder layers with a wide range of properties. The results reveal a strong correlation between energy input and the effective powder layer thickness where lower scan speed results in an increased effective powder layer thickness due to material losses. Additionally, faster recoating decreases the powder layer density, which is moderated by the median particle size where the effect is strongest for fine powders. The surface roughness of the powder layer and top part surface are influenced by the recoating speed, energy input, and particle size, and they are strongly linked to each other. This highlights the importance of considering realistic substrate surface roughnesses in both powder spreading experiments and simulations. Finally, layer properties affect the process stability, resulting in small differences in relative part density.

Role of TiC on the microstructure, tensile property and thermal stability of laser powder bed fusion fabricated AlSi10Mg alloy

The incorporation of ceramic particles is frequently employed to enhance the printability of high-strength aluminum (Al) alloys in laser powder bed fusion (L-PBF). However, their influence on the long-term thermal stability and elevated temperature mechanical properties of the Al alloy is seldom studied. This study aims to address this gap by investigating the role of micron-sized TiC particles in the microstructure, long-term thermal stability, and elevated temperature tensile properties of an L-PBF-fabricated AlSi10Mg alloy. The results indicate that highly dense TiC/AlSi10Mg samples can be fabricated, featuring fine equiaxed grains rather than the coarse columnar grains typically formed in the AlSi10Mg alloy. This columnar-to-equiaxed transition is attributed to the residual TiC and the in-situ formation of Al3Ti particles, which act as nucleating agents. Moreover, the incorporation of TiC significantly enhances the long-term thermal stability of the AlSi10Mg alloy by improving the stability of the eutectic network and retarding the coarsening of Si particles by inhibiting Si diffusion. Compared to the AlSi10Mg counterpart, the TiC/AlSi10Mg composite exhibits a higher hardness retention ratio (56 % versus 45 %) after thermal exposure at 400 °C for 192 h. The residual TiC and in-situ formed Al3Ti have high thermal stability and can impede dislocation motion, thereby contributing to enhanced long-term thermal stability. This study offers insights into the design of L-PBF ceramic-reinforced Al alloys with improved thermal stability for high-temperature applications.