Improvement Of Mechanical Properties Research Articles

Enhanced mechanical properties of molybdenum alloy originating from composite strengthening of Re and CeO2

To enhance the mechanical properties of molybdenum alloys at both room and high temperatures, Mo−14Re−1CeO2 alloy was synthesized using the powder metallurgy method, and the corresponding microstructure and mechanical properties were characterized. The results indicate that the ultimate tensile strength of Mo−14Re−1CeO2 reaches 657 MPa, with a total elongation of 35.2%, significantly higher than those of pure molybdenum (453 MPa, and 7.01%). Furthermore, the compression strength of Mo−14Re−1CeO2 at high temperature (1200 °C) achieves 355 MPa, which is still larger than that of pure molybdenum (221 MPa). It is revealed that there is a coherent interface between CeO2 and the Mo−14Re matrix with CeO2 particles uniformly distributed in both intergranular and intragranular regions. The improvements in mechanical properties are primarily attributed to the formation of Mo−Re solid solution, grain refinement, and dispersion strengthening effect of CeO2.

Section thickness effect on microstructure, mechanical and electrical properties of permanent steel mold cast eutectic Al-1.8Fe alloy

Abstract A eutectic aluminum alloy, with a composition of 1.8 wt% iron, underwent casting using permanent steel mold casting (PSMC) across three distinct section thicknesses: 2mm, 8mm, and 20mm. The microstructure of the as-cast alloy was analysed by the scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The microstructure analyses indicated that the cast Al-1.8Fe alloy consisted of the primary Al phase, eutectic Al phase, micron-sized eutectic Al-Fe phase, and nano-sized eutectic Al-Fe phase. The results of tensile testing revealed notable improvements in mechanical properties for the cast Al-1.8Fe alloy as the section thickness decreased from 20mm to 2mm. Specifically, Ultimate Tensile Strength (UTS), Yield Strength (YS), elongation (ef), modulus, toughness, resilience, and electrical conductivity increased from 85.99 MPa, 28.33 MPa, 15%, 63 GPa, 8.58 MJ/m3, 6.37 kJ/m3, 48.44 %IACS to 157.74 MPa, 84.83 MPa, 19%, 66.4 GPa, 23.87 MJ/3, 54.17 kJ/m3, 51.09 %IACS, respectively. Conversely, porosity levels decreased from 5.17% to 1.87% as thickness increased from 2mm to 20mm. The enhanced mechanical properties and electrical conductivity observed in the 2mm sample are attributed to its fine microstructure and low porosity. Additionally, SEM fractography revealed that fracture behavior in PSMC Al-1.8Fe was influenced by section thickness.

Improvement in mechanical properties of extruded Mg alloy through shape control of extrusion billet

Improvement in mechanical properties of extruded Mg alloy through shape control of extrusion billet

Pharmacological antagonism of Ccr2+ cell recruitment to facilitate regenerative tendon healing.

Successful tendon healing requires sufficient deposition and remodeling of new extracellular matrix at the site of injury, with this process mediating in part through fibroblast activation via communication with macrophages. Moreover, resolution of healing requires clearance or reversion of activated cells, with chronic interactions with persistent macrophages impairing resolution and facilitating the conversion to fibrotic healing. As such, modulation of the macrophage environment represents an important translational target to improve the tendon healing process. Circulating monocytes are recruited to sites of tissue injury, including the tendon, via upregulation of cytokines including Ccl2, which facilitates recruitment of Ccr2+ macrophages to the healing tendon. Our prior work has demonstrated that Ccr2-/- can modulate fibroblast activation and myofibroblast differentiation. However, this approach lacked temporal control and resulted in healing impairments. Thus, in the current study we have leveraged a Ccr2 antagonist to blunt macrophage recruitment to the healing tendon in a time-dependent manner. We first tested the effects of Ccr2 antagonism during the acute inflammatory phase and found that this had no effect on the healing process. In contrast, Ccr2 antagonism during the early proliferative/granulation tissue period resulted in significant improvements in mechanical properties of the healing tendon. Collectively, these data demonstrate the temporally distinct impacts of modulating Ccr2+ cell recruitment and Ccr2 antagonism during tendon healing and highlight the translational potential of transient Ccr2 antagonism to improve the tendon healing process.

Optimizing the microstructure, mechanical, and optical properties of recycled zirconia for dental applications

Efficient recycling of dental zirconia residues from computer-aided design/manufacturing processes is crucial for sustainable development in dentistry. This study employed ball milling to modify recycled zirconia powder (RZP). Initial RZP and ball-milled RZP (RZP-BM) were pre-sintered at 1000–1150 °C and then final sintered at 1500 °C. Initial RZP had irregular shapes, while RZP-BM showed finer and more uniform morphology, higher packing density, and improved de-agglomeration after 6 h of ball milling. For pre-sintered zirconia, RZP-BM samples achieved properties comparable with commercial zirconia at 1100 °C, whereas initial RZP required 1150 °C. For final sintered zirconia, initial RZP samples exhibited lower Vickers microhardness, density, strength, and transmittance, with numerous defects in its microstructure. RZP-BM samples showed significant improvement in mechanical and optical properties, comparable with commercial zirconia. This study establishes a viable approach for recycling dental zirconia residues, enhancing its properties for potential reuse as dental materials.

Design of epoxy composites via molecular orbital modulation and enhanced π-πF interactions achieving synchronous improvement of electrical and mechanical performance

The stacked aromatic rings in bisphenol A epoxy resins provide good mechanical properties and thermal stability while leading to the transport of conjugated delocalized electrons, which dramatically affects the insulation properties of the material. This contradiction leads to performance bottlenecks in epoxy-based encapsulation materials, further limiting the development of high-voltage semiconductor devices. In this study, fluorophenyl-modified epoxy monomers (FPMEPs) are designed to enrich the intermolecular interactions in an aromatic system while inhibiting the charge transport process, thereby solving the contradiction between the electrical and mechanical properties. Firstly, FPMEP with high insulation properties was designed by theoretical calculations and then synthesized by highly selective click chemistry. The fluorophenyl modulates the molecular orbitals of epoxy monomers and acts as a deep trap to inhibit charge injection and transport processes. Further, the π-πF stacking between the aromatic system and fluorophenyl enhances the interaction of the matrix molecules and solves the dispersion problem of fluorinated graphene (FG) fillers. The FPMEP/FG composites thus exhibit a considerable improvement in electrical and mechanical properties (breakdown strength of 39.8 kV/mm, dielectric loss of 0.011@50 Hz, tensile strength of 68.8 MPa, and adhesive strength of 2.15 MPa), and demonstrate good water repellency and aging durability. This matrix-filler synergistic modification strategy provides new insights into the design of insulation material.

Refinement of microstructure and improvement of mechanical properties of directed energy deposited titanium alloys by adding Fe

Elemental alloying is a validated strategy for enhancing the mechanical properties of directed energy deposited titanium alloys. However, it is still a challenge to obtain titanium alloys with both high strength and high ductility. In this work, to balance strength and ductility, the alloying element Fe was in-situ added to the TC4 melt pool during the directed energy deposited process and the effects of its content on the microstructure and mechanical performance of the TC4 alloy deposits were investigated. The results showed that the Fe additive ranging from 0.5 to 2.0wt.% were completely solid-solved in the retained β phase of TC4 alloys. Moreover, the primary β columnar grains were transformed into fully equiaxed grains. Meanwhile, the presence of Fe refined the α-laths, increased the proportion of the retained β phase, and the continuous grain boundary α (GB-α) became discontinuous. The tensile strength of the deposited alloys was continually improved with increasing Fe content, while the elongation had a peak value. When the Fe content was 1.0wt.%, the deposited alloy exhibited the best comprehensive performance, with an ultimate tensile strength of 1071MPa and an elongation of 9.3%. The enhancement of tensile strength was attributed to the solid solution strengthening and the refinement of α-laths and primary β grains. The increased proportion of retained β phase and the formation of discontinuous GB-α were beneficial for the alloy ductility. However, increased α/β interfaces inhibited dislocation movements, resulting in a decrease in ductility. The development of this alloy is important for aerospace and other fields that require high strength, high ductility and lightweight.

Mechanical property improvements of LPBF-AlSi10Mg via forging to modify microstructure and defect characteristics

Additive Manufacturing (AM) processes have versatile capabilities but are susceptible to the formation of as-cast non-equilibrium microstructures, process-induced defects, and porosity, which have deleterious effects on the mechanical performance. As part of our NSF-ERC-HAMMER program, isothermal forging was investigated as a novel post-processing technique for refining microstructure, reducing process defect severity, and thereby improving mechanical properties. Specimens of Laser Powderbed Fusion (LPBF) AlSi10Mg were fabricated over a range of process parameters and tensile tested as a baseline. Initial work focused on duplicate AM material that was then hot forged with 20 % strain to investigate the effects of isothermal forging at one temperature and strain rate on the microstructure, tensile, and fatigue properties of the as-deposited materials. The microstructures, process-induced defect populations, and tensile/fatigue properties of both as-deposited and forged materials were quantified and analysed by OM, EBSD, XCT, and SEM by various NSF-ERC-HAMMER team members. Isothermal hot forging was found to induce recrystallisation and modify process-induced defect geometry along with increasing tensile ductility. The effects of AM deposition parameters and forge post-processing conditions on LPBF AlSi10Mg will be discussed in terms of microstructure, mechanical properties, and fractography.

Impact of graphene oxide lateral sizes on the mechanical and thermal properties of carbon fiber composites

AbstractThe impact of carbon fiber (CF) composites sizing with graphene oxide (GO) to form brick‐and‐mortar structures on their mechanical properties and thermal conductivity has not been closely examined. This study systematically investigates the effect of GO sheet size on the interfacial properties and thermal conductivity of CF composites. Three sizes of GO—small (0.11 μm), medium (0.33 μm), and large (0.97 μm)—were used to modify CF surfaces via layer‐by‐layer self‐assembly, forming the brick‐and‐mortar structures. The mechanical properties were assessed through flexural tests, interlaminar shear strength (ILSS) tests and tensile tests, while thermal conductivity was measured using a thermal constant analyzer. The results revealed that medium‐sized GO (GO‐M) significantly enhanced the interfacial strength and toughness of the composites. This improvement is attributed to the orderly arrangement of GO‐M on the CF surface, which enhances stress transfer between the fiber and the matrix. In contrast, small‐sized GO (GO‐S) tended to scatter, resulting in less effective reinforcement, while large‐sized GO (GO‐L) exhibited stacking and agglomeration, limiting its reinforcement effectiveness. However, GO‐L provided the highest thermal conductivity due to the formation of continuous heat conduction pathways. These findings suggest that GO‐M offers a balanced improvement in mechanical properties, whereas GO‐L is more suitable for applications requiring high thermal conductivity. This work underscores the importance of selecting the appropriate GO sheet size to optimize the interfacial properties and thermal conductivity of CF composites, which is crucial for enhancing their performance in high‐end engineering applications, such as aerospace, automotive, and marine industries.Highlights Modification of CF composites by GO‐M sheets significantly improved toughness and strength. GO‐L sheets formed an effective heat transfer channel with the highest thermal conductivity. The study emphasized the critical role of selecting the appropriate GO sheet size to optimize the mechanical and thermal properties of CF composites.

Improvement of mechanical properties of Mg2Si phase system by doping transition metals: a first-principles study

Improvement of mechanical properties of Mg2Si phase system by doping transition metals: a first-principles study

A high toughness hydrogel with Dy3+ enhanced fluorescence properties: For visual Zn2+ detection

Rapid, portable, and sensitive detection of Zn2+ is crucial for human health. In this study, SA/PEG/Ln fluorescent hydrogels were synthesized via in situ polymerization with lanthanide metals (Tb3+/Dy3+) and PAM. The results demonstrated a significant improvement in mechanical properties (132.8 % increase in compressive properties) after rare earth doping. The addition of Dy3+ enhanced the fluorescence properties of the singly doped Tb3+ fluorescent hydrogel (maximum luminous intensity increased by 1900 cd). Monitoring changes in fluorescence intensity enabled the realization of Zn2+ detection, allowing for quick and accurate determination of zinc ion presence. Visual monitoring of Zn2+ was achieved with the assistance of a portable ultraviolet lamp.

Study on mechanical and electrical properties improvement of insulating paper modified by cellulose nanocrystals

Study on mechanical and electrical properties improvement of insulating paper modified by cellulose nanocrystals

Effects of substrate temperature and bias voltage on mechanical and tribological properties of cosputtered (TiZrHfTa)Nx films

This study investigated the effects of substrate temperature and bias voltage on the mechanical and tribological properties of cosputtered (TiZrHfTa)Nx films. A substrate temperature ranging from room temperature to 400 °C, and a bias voltage ranging from 0 to −150 V were selected as the sputtering variables. A mixture gas with a nitrogen flow ratio (fN2 = N2/[N2 + Ar]) of 0.2 was used to fabricate nitride films. Nanoindentation and wear tests were conducted to assess the performance of the fabricated (TiZrHfTa)Nx films, which formed a single face-centered cubic structure. Increasing the substrate temperature resulted in grain growth, lattice shrinkage, and nonsignificant improvements in mechanical properties. Applying a bias voltage of −150 V to the substrate increased the hardness of the fabricated film to a peak of 32.7 GPa compared with that of 29.3 GPa for the film prepared in an electronically grounded state. The (Ti0.24Zr0.22Hf0.19Ta0.35)N0.66 film prepared at a bias voltage of 0 V and substrate temperature of 400 °C exhibited the optimal combination of mechanical and tribological properties (hardness, 30.0 GPa; elastic modulus, 325 GPa; and wear rate, 1.16 × 10−5 mm3/Nm).

Mechanical property improvement of diffusion bonded ZrCx joints by chemical homogenization using Ta as the interlayer

In the present study, a transition metal Ta foil was used as the interlayer to diffusion bond ZrCx ceramics. A needle-like ζ-Ta4C3-x phase was initially formed at the interface and could be effectively dissolved into the base ceramic by reasonably tuning the bonding temperature and holding time, resulting in a chemically homogeneous joint when diffusion bonded at 1600 °C for 1 h under 20 MPa pressure. The composition of the homogeneous joints was composed of ZrCx(Ta), which is very similar to the base ceramic. The ζ-Ta4C3-x phase was found beneficial to the mechanical property of the joints due to its mechanically interlocking effect and the ability to absorb the propagation energy of microcracks. The chemically homogeneous joint had comparable four-point bending strength and nano-indentation hardness with that of the base ceramic, indicating that chemical homogenization of the joint has great potential to enhance the mechanical property of the ZrCx joints.

Harnessing the synergistic power of lignin-Ecoflex blends for enhanced performance in food packaging

In this study, a two-step chemical modification method was applied to lignin, enabling the thermal blending of lignin and Ecoflex® (PBAT) to produce films for food packaging applications. In the first step, 90 % of phenolic and carboxylic acid groups were converted into aliphatic hydroxy groups via hydroxyethylation, and in the second step, the aliphatic hydroxy groups were esterified with cinnamic acid, introducing abundant phenyl rings as well as unsaturated groups to the polymer. The modified lignin possessed an aliphatic–aromatic structure, similar to Ecoflex®, thereby enhancing the potential miscibility between these two materials. Subsequent experiments revealed that adding 20 % of modified lignin into Ecoflex® film resulted in the most significant improvement in mechanical properties, tripling the stiffness and doubling the strength. The addition of 30 % of modified lignin showed the best outcomes in UV absorption, barrier properties against oxygen and water vapor, and anti-oxidation ability. A strawberry ripening test indicated that the Ecoflex® film containing 30 % of modified lignin extended the shelf-life of strawberries from 2 days to 7 days, with better performance than the results of polyethylene bags and pure Ecoflex® films.

Improvement of Physical and Mechanical properties of High-performance Sand Concrete with different Silica Fume content

Silica fume (SF) is widely used for the improvement of several properties of cementitious materials. For this purpose, this study investigated the effect of SF content on the mechanical and durability properties of high-performance sand concrete (HPSC). The experiment work consists of the preparation of HPSC by adding different amounts of SF (0 %, 4 %, 6 %, and 8 %) as a replacement for ordinary Portland cement at a constant water-to-cement ratio of 0,35. The compressive and flexural strengths were performed on the HPSC samples with two standardised sizes of 40 mm × 40 mm × 40 mm and 40 × 40 × 160 mm, which cured during 3, 7, and 28 d. In contrast, both water absorption and water capillary absorption analyses were conducted under a prismatic size of 40 × 40 × 160 mm and cured for 28 d. Based on the test results, the optimal amount of SF was obtained using mechanical strength analysis (6 %). The results showed that at this content of SF, the compressive strength and flexural strength increased by 6,19 and 10,03 %, respectively. In contrast, the addition of SF above this concentration slightly increased the mechanical properties. However, the lowest value of water absorption was obtained for the sample with 6 % SF content. Indeed, at this concentration of SF, the water absorption and the capillarity values of HPSC samples decreased by 8,80 and 8,57 %, respectively.

DFT insight into the structural, vibrational, and electronic properties of thin [110] Ge nanowires as anodic material for Li batteries

Germanium nanowires could be used to improve as anodic materials since their charge rate is better than that of the current graphite electrodes. In this work, we present a Density Functional Theory study of the effect of interstitial Li atoms on the vibrational, electronic, and mechanical properties of ultrathin hydrogen-passivated Ge nanowires (HGeNWs) with diamond structure, grown along the [110] crystallographic direction, and with a diameter of ∼14.4 Å. The interstitial Li atoms were placed at the tetrahedral positions (Td) reported as the more favorable ones. The phonon band structure of the HGeNWs reveals the existence of high frequency vibrations due to the hydrogen atoms at the nanowire surface. The effect of one interstitial Li atom in the nanowire leads to the apparition of three flat phonon bands almost independent of the collective vibrational states of the nanowire, reflecting a weak interaction between the Li atom and the neighboring ones; and a shift of the high vibrational modes to lower frequencies that results in more dispersive states. The electronic band structure confirms a transition from semiconducting to metallic behavior by adding a single Li interstitial atom per unit cell. The formation energies indicate that the nanowires with interstitial Li atoms are stable, and the average binding energy per Li atom slightly increases as a function of the concentration of Li atoms. The insertion of Li atoms in the nanowire leads to a volumetric expansion, without fracture or broken bonds. Even more, the redistribution of the electronic charge due to the Li atoms give the Ge-Ge bonds more axial elasticity and the values of the modulus of Young are almost constant for all studied concentrations of Li atoms. These theoretical results indicate an improvement of mechanical and electronic properties of Ge nanowires through the addition of interstitial Li atoms that could be important for their use as anodes in rechargeable Li batteries.

Improvement of Formation, Microstructure and Mechanical Properties of TIG Welded TC4 Titanium Alloy by Ultrasonic Coaxial Radiation

Improvement of Formation, Microstructure and Mechanical Properties of TIG Welded TC4 Titanium Alloy by Ultrasonic Coaxial Radiation

Cemented sand under hollow cylinder multiaxial loading

Improvement of granular soils mechanical properties can be achieved by the addition of bonding agents. In this research, low amount of Portland cement was added to a sand and its beneficial shear strengthening effects were evaluated under a range of multiaxial stress paths. The influence of the orientation of the principal axes of stress and strain on the stress-strain response and failure of cemented sand has only been scarcely investigated. Therefore, this experimental investigation reports the results of a series of consolidated drained hollow cylinder torsional tests with constant principal stress path direction, ασ, varying from 0° to 90° Results were compared with the shear behaviour of the uncemented sand tested under similar loading conditions. Results show that the addition of cement to the sand matrix increases the soil strength for all multiaxial stress path directions. The suitability of two multiaxial strength criteria for reproducing the shape of the failure envelope as a function of the orientation of principal stress axis ασ has also been analysed.

Unprecedented high-strength and ductility in Ni nanograined metal via minor phosphorus alloying

A bulk Ni nanograined (NG) metal with 2 at.% P alloying was synthesized via electrodeposition, leading to notable improvements in mechanical properties compared to its NG Ni counterpart. The reduction in grain size from 104 nm to 45 nm, accompanied by a remarkable increase in yield strength from 620 MPa to 1550 MPa, signifies the efficacy of phosphorus (P) incorporation. Remarkably, the ductility of NG Ni-P remains robust at 16 %, comparable to NG Ni. These enhancements stem from the synergistic effects of P, which not only refine grain size but also promote the formation of a dense network of growth stacking faults, dislocations, and growth twins within the as-deposited NG Ni-P structure.