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The superior physicochemical properties of layered double hydroxides (LDHs) sets them apart from traditional polylactic acid (PLA) fillers. However, achieving efficient dispersion of LDHs within the PLA matrix poses a challenge in the fabrication of PLA/LDHs nanocomposites. In order to enhance the dispersion of LDHs in the PLA matrix and improve their compatibility with PLA, in this study sodium stearate (SS) and sodium dodecyl sulfate (SDS) were used as surface modifiers and intercalation modifiers for LDHs, respectively. Notably, the strategy of intercalation-surface combined modification for LDHs nanofillers in PLA was explored for the first time. Furthermore, the resulting PLA/LDHs nanocomposites were prepared via a sonication-assisted solution compounding method. The results indicate that the addition of LDHs modified through different methods and concentrations affects not only the thermal properties and crystallinity of the PLA/LDHs composites, but also improves the tensile strength and elongation at break of PLA. Notably, the PLA_LDH_SDS_SS_9% composite exhibited an elongation at break that was 230% higher than neat PLA. This study fills a research gap in the field of PLA/LDHs nanocomposites and establishes a significant foundation for the future preparation and application of these.

Additive manufacturing (AM) has gained attention in recent decades. Due to excellent mechanical and thermal properties, pure copper and its alloys are widely in nuclear and aerospace industries. CuCrZr and CuCrNb are precipitation hardenable alloys. The present work provides a comprehensive overview of current research works on CuCrZr and CuCrNb alloys built by various AM processes (especially laser powder bed fusion, L-PBF). Due to high reflectivity for near infrared laser and high thermal conductivity, it is still challenging to build copper alloys by conventional L-PBF process. Therefore, three approaches to enhance the absorptivity of the alloys have been discussed. The microstructure, including texture and precipitates have been discussed. The mechanical, electrical and thermal properties at room temperature and high temperature, anisotropic properties, and post-heat-treatments have been discussed in the review. In addition, the outlook of the AM-ed CuCrZr and CuCrNb alloys has been highlighted.

Carbon materials reinforced copper matrix composites with excellent mechanical properties, high thermal conductivity (TC) and suitable coefficient of thermal expansion (CTE) are expected to meet the urgent need for the thermal management materials with structural stability and efficient heat dissipation in civil and military fields. In this work, the tungsten-copper (W-Cu) composite coating was deposited on the graphite flakes (GFs) by the impregnation-reduction and ultrasonic-assisted electroless plating. Meanwhile, the W-Cu coated GFs reinforced Cu matrix composites (GFs(W-Cu)/Cu) were also prepared by the vacuum hot-pressing sintering. Based on the microstructure and surface analysis, the interfacial bonding has changed from the simple mechanical connection to the mechanical-metallurgical synergy. As for the three-point bending and uniaxial tensile tests, the largest in-plane, through-plane flexural strength and tensile strength of the GFs(W-Cu)/Cu composite can achieve the values of 189.6 ± 3.8, 172.3 ± 4.2 and 91.9 ± 2.6 MPa, respectively. Among the GFs(W-Cu)/Cu composites, the ultrahigh in-plane TC and lowest through-plane CTE can reach 929.8 ± 5.0 Wm−1K−1 and 6.3 ± 0.2 ppmK−1 respectively, and the better thermal response rate can be 0.67 °C·s−1. In conclusion, an effective way to develop the structural and functional integrated carbon-based thermal management materials can be provided.

An entropy-stabilization strategy was applied to engineer a novel thermal insulating material by establishing a single-phase solid solution with the formula of (Y1/2Yb1/2)2(Ti1/3Zr1/3Hf1/3)2O7 (YYHEO). Structural analysis revealed that this material exceeded the typical substitutional solubility limit, even with a significant atomic size difference, where the conventional determination rule was defied. YYHEO exhibited a lower glass-like thermal conductivity due to its highly disordered crystal structure and the specific design strategy. The coefficient of thermal expansion and mechanical properties (e.g. elastic modulus and hardness) were comparable to conventional materials, suggesting that YYHEO is a promising candidate for application as a new thermal insulating material.

[Display omitted] • The as-deposited AlCrFeCoNiCu 0.5 films were annealed at 500 °C for up to 72 h. • Four new phases were formed during the 72 h of annealing. • The formation of a new heterogeneous nanocomposite thin film was revealed. • A 30% enhancement of mechanical properties was achieved after 72 h annealing. • The as-annealed thin films exhibited superior thermal stability. High entropy alloy (HEA) films offer excellent mechanical properties due to their random solid solution structure. However, their large grain boundary volume fraction can cause thermal instability, resulting in phase decomposition that affects their high-temperature performance. Nevertheless, it remains an interesting question whether phase decomposition can be used as a processing tool to create new HEA materials. In this study, AlCrFeCoNiCu0.5 HEA thin films were fabricated and annealed at 500 °C for up to 72 h. The 72-hour annealed thin film exhibited a 30 % increase in mechanical properties, exceeding most other HEA thin films. Characterization using X-ray and electron microscopy revealed a decomposition-induced phase transformation, which produced four new phases, including Cu-rich FCC phase, Cr-rich BCC phase, and ordered B2 phase of AlNi and FeCo. The enhanced mechanical properties were due to back stress strengthening and BCC + B2 phase strengthening. The 72-hour annealed thin film also showed excellent thermal stability through a new round of annealing, exhibiting a low variation in microstructure and chemical composition after being annealed at 500 °C for 100 h. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel Sc/Zr/Ti/Er modified Al-Cu alloy was successfully fabricated by wire-arc directed energy deposition technology. • The fine equiaxed grain structure was obtained due to the heterogeneous nucleation caused by the primary Al3X dispersoids. • Homogenization prefabricates more Al3X dispersoids, which promote the transition from θ″ to θ′ precipitate. • Homogenization ripens the existing pores, resulting in a better tensile isotropy. In this study, a novel Sc/Zr/Ti/Er-modified 2219 aluminum alloy was designed and wall-shaped components were then fabricated by wire-arc directed energy deposition (DED). Due to the heterogeneous nucleation promoted by primary Al 3 X dispersoids, the as-deposited alloy exhibits a highly equiaxed fine grain structure. Two heat treatment schedules were conducted to tailor the strength and thermal stability of the alloy. Compared with the classical T6 heat treatment, the additional homogenization step before the T6 heat treatment (HT6) prefabricated more Al 3 X dispersoids, which indirectly promoted the transition from θ″ precipitates to θ′ precipitates, resulting in a slight reduction in strength. However, this homogenization step helps to avoid the aggregation of pores by promoting pores ripening and significantly alleviates the anisotropy of ductility. In addition, the better thermal stability of the HT6 heat treated alloy is due to more Al 3 X dispersoids and finer θ′ precipitates with high coarsening resistance caused by the segregation of Sc and Mn at the θ′/Al interface during thermal exposure. In general, the wire-arc DEDed micro-alloyed 2219 Al alloy exhibits a promising combination of strength and ductility after heat treatment and its mechanical properties are superior to those of the wrought micro-alloyed Al-Cu alloys. [ABSTRACT FROM AUTHOR]

[Display omitted] • The LDHs nanofillers for PLA were successfully modified by intercalation-surface combined modification strategy. • Modified LDHs can alter the crystallinity of PLA/LDHs nanocomposites within the range of 10.1% to 47.3%. • The incorporation of organically modified LDHs simultaneously enhances the tensile strength and elongation of PLA composites. • The addition of LDHs modified through combined modification can enhance the elongation at break of PLA by up to 230%. The superior physicochemical properties of layered double hydroxides (LDHs) sets them apart from traditional polylactic acid (PLA) fillers. However, achieving efficient dispersion of LDHs within the PLA matrix poses a challenge in the fabrication of PLA/LDHs nanocomposites. In order to enhance the dispersion of LDHs in the PLA matrix and improve their compatibility with PLA, in this study sodium stearate (SS) and sodium dodecyl sulfate (SDS) were used as surface modifiers and intercalation modifiers for LDHs, respectively. Notably, the strategy of intercalation-surface combined modification for LDHs nanofillers in PLA was explored for the first time. Furthermore, the resulting PLA/LDHs nanocomposites were prepared via a sonication-assisted solution compounding method. The results indicate that the addition of LDHs modified through different methods and concentrations affects not only the thermal properties and crystallinity of the PLA/LDHs composites, but also improves the tensile strength and elongation at break of PLA. Notably, the PLA_LDH_SDS_SS_9% composite exhibited an elongation at break that was 230% higher than neat PLA. This study fills a research gap in the field of PLA/LDHs nanocomposites and establishes a significant foundation for the future preparation and application of these. [ABSTRACT FROM AUTHOR]

[Display omitted] • The various AM-ed high-heat-flux copper alloys CuCrZr and CuCrNb alloys are built by different processes, including L-PBF, EB-PBF, LP-DED, AW-DED and HLADED processes. The optimization of building parameters, the approaches to enhance the absorptivity of copper alloys are stressed. • The microstructure, crystallographic texture, and precipitates of AM-ed CuCrZr and CuCrNb alloys are summarized. The precipitates mainly include Cr, Cu x Zr y , and ZrO 2 particles for AM-ed CuCrZr, and Cr and Cr 2 Nb particles for AM-ed CuCrNb alloys, respectively. • The mechanical and thermal properties of various AM-ed CuCrZr and CuCrNb alloys are presented, including anisotropic properties, the effect of heat treatments on the properties and the properties at high temperature. Additive manufacturing (AM) has gained attention in recent decades. Due to excellent mechanical and thermal properties, pure copper and its alloys are widely in nuclear and aerospace industries. CuCrZr and CuCrNb are precipitation hardenable alloys. The present work provides a comprehensive overview of current research works on CuCrZr and CuCrNb alloys built by various AM processes (especially laser powder bed fusion, L-PBF). Due to high reflectivity for near infrared laser and high thermal conductivity, it is still challenging to build copper alloys by conventional L-PBF process. Therefore, three approaches to enhance the absorptivity of the alloys have been discussed. The microstructure, including texture and precipitates have been discussed. The mechanical, electrical and thermal properties at room temperature and high temperature, anisotropic properties, and post-heat-treatments have been discussed in the review. In addition, the outlook of the AM-ed CuCrZr and CuCrNb alloys has been highlighted. [ABSTRACT FROM AUTHOR]

[Display omitted] • Compact and nanogranular ZrCu/O films were deposited by pulsed laser deposition and annealed to investigate thermal stability. • Nanogranular films crystallize at 300 °C, while the crystallization of compact films occurs >420 °C. • The Young's modulus and hardness increase with annealing temperatures due crystallization process, reaching 180 and 14 GPa for nanogranular films. • The residual stresses of compact films increase with annealing temperature, while for nanogranular ones they reach a maximum at 420 °C, indicating a complete crystallization. • The evolution of structural/mechanical properties is studied, considering film morphology, local chemistry and free volume. Binary ZrCu nanocomposite amorphous films are synthetized by pulsed laser deposition (PLD) under vacuum (2 × 10−3 Pa) and 10 Pa He pressure, leading to fully amorphous compact and nanogranular morphologies, respectively. Then, post-thermal annealing treatments are carried out to explore thermal stability and crystallization phenomena together with the evolution of mechanical properties. Compact films exhibit larger thermal stability with partial crystallization phenomena starting at 420 °C, still to be completed at 550 °C, while nanogranular films exhibit early-stage crystallization at 300 °C and completed at 485 °C. The microstructural differences are related to a distinct evolution of mechanical properties and residual stress, with compact TFMGs showing the highest values of Young's modulus (157 GPa), hardness (12 GPa), strain rate sensitivity (0.096), and local residual stress (+691 MPa) upon annealing at 550 °C, while nanogranular films reach the maximum values of mechanical properties at 485 °C followed by relaxation at higher temperatures due to complete crystallization. We show that PLD in combination with post-thermal annealing can generate different families of amorphous films with varying nanoscale morphologies, resulting in tunable mechanical properties and thermal stability, which can thus be used for designing novel film configurations for different fields of application. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of various steatite ceramics with porosities up to 30% using different types and concentrations of renewable plant fiber products. • 3D X-ray microscopy enabled a non-destructive investigation of isolated pores (≤350 µm) and large pore structures (greater than 1000 µm). • Extracted pore network models facilitated the characterization of the specific pore parameters induced by the different pore-forming agents and contents. • The use of the longer fiber product (≤350 µm) indicated a limitation of the processability at concentrations around 10 wt%. • Experimentally validated effective medium modeling gave access to the thermo-mechanical properties in dependence of pore space parameters. A large number (greater than 150) of porous steatite ceramic rods were prepared using different types of renewable plant fiber products as pore-forming agent with mass contents ranging from 2 to 10%. In addition, dense steatite ceramics were synthesized for comparison within a gas furnace at sintering temperatures between 1300 and 1350 °C. High-resolution 3D X-ray microscopy facilitated a non-destructive, direct investigation of the three-dimensional pore space and microstructure. By using image-based pore space analysis, various pore space parameters, such as, e.g., pore volume, pore-size distribution, and pore connectivity were determined. In addition to the characterization of the pore space, phase analysis, structural and chemical investigations were carried out by X-ray powder diffraction, electron microscopy, Fourier-transform infrared, Raman and X-ray spectroscopy. Finally, to evaluate the influence of characteristics on the physical properties, elastic, strength and thermal properties were determined. With the increase of porosity, the flexural strength and thermal conductivity values decrease from σ f = 123 ± 8 to 37 ± 5 MPa and λ = 3.22 ± 0.02 to 1.77 ± 0.02 W/(m·K), respectively. The obtained experimental results were discussed by means of micromechanical models, highlighting the effect of pore-space morphologies on the physical performance of porous steatite ceramics. [ABSTRACT FROM AUTHOR]

[Display omitted] • A W-Cu composite coating was deposited on the graphite flakes by combing the impregnation reduction and ultrasonic-assisted electroless plating. • The W-Cu composite coating can enhance the GFs/Cu interfacial bonding from the simple mechanical connection to the mechanical-metallurgical synergy. • For the GFs(7 W-Cu)/Cu composites, the in-plane flexural strength and TC reached 189.6 ± 3.8 MPa and 929.8 ± 5.0 Wm−1K−1, respectively. Carbon materials reinforced copper matrix composites with excellent mechanical properties, high thermal conductivity (TC) and suitable coefficient of thermal expansion (CTE) are expected to meet the urgent need for the thermal management materials with structural stability and efficient heat dissipation in civil and military fields. In this work, the tungsten-copper (W-Cu) composite coating was deposited on the graphite flakes (GFs) by the impregnation-reduction and ultrasonic-assisted electroless plating. Meanwhile, the W-Cu coated GFs reinforced Cu matrix composites (GFs(W-Cu)/Cu) were also prepared by the vacuum hot-pressing sintering. Based on the microstructure and surface analysis, the interfacial bonding has changed from the simple mechanical connection to the mechanical-metallurgical synergy. As for the three-point bending and uniaxial tensile tests, the largest in-plane, through-plane flexural strength and tensile strength of the GFs(W-Cu)/Cu composite can achieve the values of 189.6 ± 3.8, 172.3 ± 4.2 and 91.9 ± 2.6 MPa, respectively. Among the GFs(W-Cu)/Cu composites, the ultrahigh in-plane TC and lowest through-plane CTE can reach 929.8 ± 5.0 Wm−1K−1 and 6.3 ± 0.2 ppmK−1 respectively, and the better thermal response rate can be 0.67 °C·s−1. In conclusion, an effective way to develop the structural and functional integrated carbon-based thermal management materials can be provided. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel high-entropy oxide (YYHEO) was engineered with significant mass disorder. • YYHEO exhibited glass-like low thermal conductivity (1.27 W/m∙K). • YYHEO exceeded typical substitutional solid solubility limit even with a significant atomic size difference (>50%). • YYHEO shows thermal stability even at elevated temperature (1500 ° C) without any phase degradation. • Thermophysical properties were compatible with YSZ (CTE: 10.08 × 10−6 K−1, E : 218.21 ± 3.64 GPa and H : 14.42 ± 0.5 GPa). An entropy-stabilization strategy was applied to engineer a novel thermal insulating material by establishing a single-phase solid solution with the formula of (Y 1/2 Yb 1/2) 2 (Ti 1/3 Zr 1/3 Hf 1/3) 2 O 7 (YYHEO). Structural analysis revealed that this material exceeded the typical substitutional solubility limit, even with a significant atomic size difference, where the conventional determination rule was defied. YYHEO exhibited a lower glass-like thermal conductivity due to its highly disordered crystal structure and the specific design strategy. The coefficient of thermal expansion and mechanical properties (e.g. elastic modulus and hardness) were comparable to conventional materials, suggesting that YYHEO is a promising candidate for application as a new thermal insulating material. [ABSTRACT FROM AUTHOR]

• Highly filled PBT/alumina composites were toughened via reactive processing. • Excellent thermal conductivity and strength were preserved after modification. • Percolating network and yield behavior were determined by three rheological criteria. • More stable phase structure was confirmed via creep-recovery test after reactive compatibilization. • Improved toughness was attributed to interfacial interaction and stress transfer. Unlabelled Image High filler content is the prerequisite for imparting specific properties to polymeric composite. However, serious mechanical properties degradation happened in this kind of material due to the inevitable reduction of material cohesion. In this work, highly filled poly(butylene terephthalate)/ alumina (PBT/Al 2 O 3) composites were modified by directly melt mixing with a reactive compatibilizer ethylene–methyl acrylate–glycidyl methacrylate terpolymer (E-MA-GMA). The modified samples presented greatly enhanced elongation at break and impact response, simultaneously preserved their tensile strength and high thermal conductivity. The reactive compatibilization between PBT and Al 2 O 3 spheres was confirmed by SEM, FTIR, and rheology characterizations. Three rheology criteria plots demonstrated that the filler percolating network and apparent yield behavior occurred in the ternary PBT/Al 2 O 3 /E-MA-GMA composites melt. It is believed that enhanced particle-matrix interfacial interaction and stress transfer caused by E-MA-GMA endowed this highly filled composite improved toughness. This study suggests the potential application of E-MA-GMA elastomer to resolve the mechanical properties degradation in highly filled polymeric composites. [ABSTRACT FROM AUTHOR]

As phase change functional polymer composites, polydimethylsiloxane (PDMS) and paraffin composites exhibit excellent performance on temperature dependent thermal and mechanical properties. In this paper, PDMS/paraffin composites with uniform microstructure are prepared by the melting mixing method with paraffin as filler and PDMS as matrix. The modification of PDMS by paraffin components owns both advantages on excellent flexibility and heat absorption capacity. Systematic experiments results are performed to illustrate the DSC specter, stress-strain curves and other properties varying with temperature. The obtained composites can be an ideal material for soft thermal management substrate of flexible electronics or phase change heat sink of batteries and this study might be helpful for the design and fabrication in the wide potential applications. Image 1 • Composites thermal management mechanism is paraffin solid-liquid phase transition that absorbing exceeding heat energy. • Composites comprising 30 wt % paraffin can be used as flexible thermal management substrate for epidermal electronics. • Phase transition, thermal management and transmittance change of the composites occur at the paraffin melting point. • Paraffin melting is the reason for viscoelastic transition and transmittance change with temperature. [ABSTRACT FROM AUTHOR]

Selective Laser Melting (SLM) is an Additive Manufacturing (AM) process based on the local fusion of powdered metal. SLM requires support structures that enable heat transfer and structural support during fabrication while being frangible to enable removal. Despite the criticality of support structures, very little quantitative data exists to characterise their behaviour. AlSi10Mg is an important SLM alloy which is particularly appropriate for laser applications due to its ease of processing. Block support structures are the most versatile of the commercially implemented support structure designs. This research presents an experimental study of the mechanical strength and numerical analysis of the thermal behaviour during SLM fabrication of ALSi10Mg block support structures. It was found that: support structure peel strength is significantly lower than normal strength due to fundamentally different failure mechanisms; support strength is influenced by height; and, reduced support spacing increases heat transfer and load bearing capability. Design equations were generated to enable prediction of the strength of a given support structure. This previously unavailable data allows AM designers to unambiguously specify support structures that are optimal for a specific design scenario. Furthermore, these insights potentially allow the redesign of block support structures such that response is independent of geometry. Unlabelled Image • Analysis of the mechanical strength and thermal properties of AlSi10Mg block support structures fabricated by SLM. • The peel strength of a support structure is significantly less than its tensile strength. • The strength of a support structure is inversely proportional to its height. • Reducing support spacing increases heat transfer capability. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM), particularly Selective Laser Melting (SLM) has enabled development of lattice structures with unique properties. Through control of various parameters lattice structures can produce unique mechanical, electrical, thermal and acoustic properties, and have received much research attention. Despite the increasing volume of published data on the mechanical response of specific SLM lattice structures, there exists no overarching analysis. This work addresses this identified deficiency by providing a comprehensive summary of the experimental data reported on the mechanical response of SLM lattice structures. The design, fabrication and performance of SLM lattice structures are reviewed and the quality of data reported is analysed to inform best-practice for future studies. This comprehensive data summary enables meta-analysis of the reported mechanical performance of SLM lattice structures, providing insight into the bounds of their technical capabilities. Correlations were identified between the relative density and mechanical properties of many unit cell topologies consistent with the predictions of the Gibson-Ashby model, indicating its usefulness in describing and predicting the behaviour of SLM lattice structures. This review provides designers with a compiled resource of experimental data and design for AM tools to inform future design applications of SLM lattice structures and facilitates their further commercial adoption. Unlabelled Image • A review of the design, fabrication and mechanical performance of Selective Laser Melting (SLM) lattice structures. • Reported data on the mechanical performance and properties of a broad range of SLM lattice structures is compiled. • Meta-analysis of reported data allows insights into the applicability of the Gibson-Ashby model to SLM lattice structures. [ABSTRACT FROM AUTHOR]