Superior Elongation Research Articles

The integrated effect of grain configuration and δ phase on micro-scaled mechanical stability of nickel-based superalloy foil

The variety and complexity of the size effect make it difficult to predict the plastic deformation behavior of foil. In this study, 0.08 mm foils with different thickness-to-grain size ratios (t/d) and δ phase distribution were obtained by adjusting the rolling and annealing processes, and the microstructure evolution before and after tensile deformation was investigated. The results show that with the decrease of the t/d ratio, the reduced grain layers number in the thickness direction facilitates grain rotation and grain boundary sliding, which accelerates the dislocation annihilation and leads to poor work hardening ability and low flow stress. Meanwhile, the lack of restrictions between adjacent grains leads to the rapid expansion of cracks after void nucleation, mainly manifested as brittle fractures. The diffuse δ phase and fine grain enhance the constraining effect on dislocations and promote dislocation proliferation and interactions. The increased number of grain layers coordinates the deformation and contributes to an increase in the Schmid factor, which supports the sliding system opening and exhibits a superior elongation of 18.1 %. The uniform δ phase exhibits good deformation compatibility and alleviates the stress concentration during the deformation process, and the interaction between neighboring grains promotes the development of uniform dimples after void nucleation, exhibiting a dominant ductile fracture. This study provides a new idea for the regulation of foil mechanical properties.

Synergistic antibacterial material of cetylpyridinium/Cu2+/sepiolite and its application in thermoplastic polyurethane films

Seeking non-antibiotic solutions against bacterial infections has become a global priority. Therefore, this work employs sepiolite as the carrier to load cetylpyridinium (CP+) and Cu2+, constructing a CP+/Cu2+/sepiolite (PCS) system with excellent antibacterial and application properties. Sepiolite, serving as a micro-container for storing antibacterial agents, enhances their thermal stability and realizes their “burst + sustained” release. Antibacterial agents improve the organic compatibility of sepiolite and provide a synergistic antibacterial effect. With the released antibacterial agents and contact inactivation effect, PCS at 10 mg/L and 75 mg/L achieve 100 % inactivation of Staphylococcus aureus and Escherichia coli within 120 min, respectively. Furthermore, the sepiolite carrier with an intact fibrous structure facilitates the loading-release and antibacterial activity of agents in PCS. The obtained PCS disperses uniformly in thermoplastic polyurethane and binds tightly with it, improving its mechanical properties. Film of ST-10wt%PCS with 10 wt% PCS inactivates 100 % of Staphylococcus aureus and 93.0 % of Escherichia coli in 4 h, while exhibiting superior elongation at break (263 %) and tensile strength (35 MPa) compared to the pure film (242 % and 30 MPa). Thus, it is evident that the resulting PCS holds promise for the direct use or manufacture of functional products to combat bacterial infections.

Semi-solid rheo-diecast Mg-xGd-3Y–1Zn-0.4Zr (wt%) alloys and their comparison with conventional HPDC alloys

This work systematically investigated the microstructure and mechanical properties of Mg-xGd-3Y–1Zn-0.4Zr (wt%) alloys prepared via rheo-diecasting (RDC) in comparison to those of conventional high pressure die casting (HPDC) alloys, and revealed their differences in microstructure, casting defects, and mechanical properties. The microstructure of the as-cast RDC Mg-xGd-3Y–1Zn-0.4Zr (wt%) alloys is primarily composed of α-Mg and Mg3(Gd,Y,Zn) eutectic phases. Of the four alloys studied, the GWZ831K and GWZ1431K alloys exhibit the best elongation (EL: 6.4±1.3 %) and the highest strengths (UTS: 270±9 MPa; YS: 201±5.7 MPa), respectively. The GWZ831K alloy exhibits a quasi-cleavage fracture during room-temperature tensile tests, whereas the GWZ1431K alloy demonstrates a brittle fracture. The phase composition of conventional HPDC alloys is fundamentally the same as that of RDC alloys, but their grains and eutectic phases differ in morphology and are smaller in size. Oxide films are frequently found in conventional HPDC castings, but neither oxide films nor pore defects are observed in RDC alloys. Compared to conventional HPDC alloys, RDC alloys have better elongation but lower strength. The lower strength of RDC alloys compared to HPDC alloys can be attributed to larger grains and eutectic phases, along with fewer stacking faults (SFs), resulting in limited strengthening effects of grain boundaries, eutectic second phases and SFs. In contrast, RDC alloys exhibit superior elongation compared to HPDC alloys due to the elimination of oxide films and pore defects, as well as the excellent ductility of the α-Mg matrix that can effectively coordinate deformation.

NIR-triggered self-healing SiO2/melanin coatings with enhanced corrosion-resistant and mechanical robustness

Polymer coatings are inherently susceptible to deformation and irreversible damage when they are subjected to external forces during service. Self-healing coatings integrated with exceptional mechanical robustness and corrosion resistance are essential for industrial applications but have been deemed challenging. Here, we present a NIR-triggered self-healing coating by combining a toughness epoxy network with melanin-modified silica (MMS). Moreover, to investigate the impact of pore size and porosity of silica on the corrosion protection performance, three types of various silica particles are selected as building blocks. The melanin-modified fumed silica/epoxy coatings demonstrate superior elongation (275 %), outstanding tensile strength (5.31 MPa) and high toughness (7.37 MJ·m3). Moreover, the introduction of the MMS can not only improve the anticorrosion performance (|Z|0.01 Hz value of 1.24 × 1010 Ω·cm2) but also realize fast photo-thermal repair (60 s). Our strategy furnishes a universal layout prototype for the manufacture of robust self-healing coatings with a scalable and cost-effective preparation method.

Preparation and Characterization of High-Density Polyethylene with Alternating Lamellar Stems Using Molecular Dynamics Simulations.

Mechanical recycling is the most efficient way to reduce plastic pollution due to its ability to maintain the intrinsic properties of plastics as well as provide economic benefits involved in other types of recycling. On the other hand, molecular dynamics (MD) simulations provide key insights into structural deformation, lamellar crystalline axis (c-axis) orientations, and reorganization, which are essential for understanding plastic behavior during structural deformations. To simulate the influence of structural deformations in high-density polyethylene (HDPE) during mechanical recycling while paying attention to obtaining an alternate lamellar orientation, the authors examine a specific way of preparing stacked lamella-oriented HDPE united atom (UA) models, starting from a single 1000 UA (C1000) chain of crystalline conformations and then packing such chain conformations into 2-chain, 10-chain, 15-chain, and 20-chain semi-crystalline models. The 2-chain, 10-chain, and 15-chain models yielded HDPE microstructures with the desired alternating lamellar orientations and entangled amorphous segments. On the other hand, the 20-chain model displayed multi-nucleus crystal growth instead of the lamellar-stack orientation. Structural characterization using a one-dimensional density profile and local order parameter {P2(r)} analyses demonstrated lamellar-stack orientation formation. All semi-crystalline models displayed the total density (ρ) and degree of crystallinity (χ) range of 0.90-0.94 g/cm-3 and ≥42-45%, respectively. A notable stress yield (σ_yield) ≈ 100-120 MPa and a superior elongation at break (ε_break) ~250% was observed under uniaxial strain deformation along the lamellar-stack orientation. Similarly, during the MD simulations, the microstructure phase change represented the average number of entanglements per chain (<Z>). From the present study, it can be recommended that the 10-chain alternate lamellar-stack orientation model is the most reliable miniature model for HDPE that can mimic industrially relevant plastic behavior in various conditions.

Synergistic Effects of 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-Based Derivative and Modified Sepiolite on Flame-Retarded Poly (Ethylene Oxide)-Poly (Butylene Adipate-Co-Terephthalate) Composites.

A 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-based derivative (PN-DOPO) combined with aluminium phosphates-coated sepiolite (Sep@AlPO4) was used to improve the flame retardance, thermal stability and mechanical performances of poly (ethylene oxide) (PEO)/poly (butylene adipate-co-terephthalate) (PBAT) blends. The synergistic effects of PN-DOPO and Sep@AlPO4 on flame-retarded PEO/PBAT composites were systematically discussed. Results indicated that introducing 5 wt% Sep@AlPO4 with 10 wt% PN-DOPO into PEO/PBAT achieved a V-1 rating for the UL-94 test and increased the limiting oxygen index value to 23.7%. Moreover, the peak heat release rate (p-HRR), average HRR and total heat release values of PEO/PBAT/PN10%/Sep5% composites decreased by 35.6%, 11.0% and 23.0% compared with those of PEO/PBAT, respectively. Thermogravimetric analysis (TGA) results confirmed that PN-DOPO/Sep@AlPO4 enhanced the initial thermal stability and char yield of PEO/PBAT matrix, and TGA/Fourier transform infrared spectrometry results revealed that the composites exhibited the characteristic absorption peaks of phosphorous-containing groups and an increase in gas-phase volatiles during thermal degradation. The morphological structures of the residues indicated that PN-DOPO and Sep@AlPO4 mixtures produced a more dense and continuous char layer on the composite surface during burning. Rheological behaviour revealed that higher complex viscosity and modulus values of PEO/PBAT/PN-DOPO/Sep@AlPO4 sample could also promote the crosslinking network structure of condensed phases during combustion. Furthermore, the PEO/PBAT/PN-DOPO/Sep@AlPO4 composites exhibited superior elongation at break and flexural performance than the PEO/PBAT system. All results demonstrated that the PEO/PBAT system modified with PN-DOPO/Sep@AlPO4 showed remarkable flame retardance, and improved thermal stability and mechanical properties, indicating its potential application in areas requiring fire safety.

Investigation of microstructures and high-temperature tensile behavior of heat treated GTD222 nickel-based superalloy prepared by selective laser melting

In this study, various heat treatment methods including direct aging and solution aging were performed on the selective laser melted (SLMed) GTD222 nickel-based superalloy, and the microstructures and high-temperature tensile behavior of the superalloys were systematically investigated. The results indicate that, in comparison to the as-deposited superalloy, both direct aging and solution aging lead to a significant enhancement in high-temperature strength and ductility. The directly aged superalloy exhibits a higher yield strength, while the solution-aged ones displays superior elongation. Specifically, at a tensile temperature of 760 °C, the superalloy subjected to a solution treatment at 1240 °C demonstrates the most favorable tensile properties, boasting a tensile strength of 835 MPa, an elongation rate of 6.5 %, and a reduction in area of 13 %. This study also provides a detailed discussion of the high temperature tensile behavior of the SLMed GTD222 superalloy after heat treatment.

Assessment of Elongation of the Mesocotyl-Coleoptile and Biomass in Parents and Crosses of Corn Seedlings of the High Valleys of Mexico

The elongation of the mesocotyl and the coleoptile and other seedling traits were analyzed from 16 hybrids of two seed sizes, five varieties and a control. Sowing was conducted in sand beds during the S-F 2020 cycle, where nine genotypes were identified that differed in the elongation of the mesocotyl: long (H-48, HS-2 and Promesa); medium (H-44-H-52 and H-70); and short (H-49 AE, H-40 and H-32). A total of 36 possible crosses were obtained between these nine parents, which were established in the S-S 2021 cycle, and on sand beds. Results show that seed size affected (p&lt; 0.05) the speed and percentage of emergence, the elongation of mesocotyl–coleoptile, the biomass and the heterosis in parents and their crosses. The H-48 hybrid presented greater speed and percentage of emergence and elongation of the mesocotyl and the coleoptile with both seed sizes. The highest dry weight of mesocotyl, coleoptile, roots, and leaves was found in the hybrids Promesa and H-48. The crosses between parents with contrasting mesocotyl presented superior elongation and dry weight (p ≤ 0.05) compared to their parents, with the long × long (1 × 2, 1 × 3 and 2 × 3) crosses standing out for all the traits measured. A strong positive association was obtained (p ≤ 0.01) between the elongation of the mesocotyl–coleoptile, the percentage of emergence, and the production of total dry matter in parents and their crosses.

Achieving synergy of strength and ductility in powder metallurgy commercially pure titanium by a unique oxygen scavenger

Excessive interstitial oxygen (O) contamination, usually causing a dramatic loss of ductility, remains a longstanding challenge for titanium (Ti) and its alloys. Here, we propose to solve this critical problem by adding a minor CaC2 oxygen-scavenger via a simple powder metallurgy (PM) pressureless sintering approach. It is found that the surface oxide layer of hydride-dehydride (HDH) Ti powder begins to dissolve into the Ti matrix between 700 °C and 800 °C during the PM sintering process. The incorporation of CaC2 can react with the surface oxide layer (617-676 °C) prior to its active dissolution and form micrometer-sized TiC and nano-sized CaTiO3 particles, significantly refining the α-Ti grains and creating clean and well-bonded interface with Ti matrix. Therefore, the unique oxygen-scavenging effect by CaC2 produces high strength and superior ductility for Ti alloy. Even with an initially high oxygen content (∼4000 ppm), the Ti-0.4 wt.%CaC2 sample still exhibits a high ultimate tensile strength of 621±25 MPa and superior elongation of 29.3±2.6%, respectively. These values correspond to an increase of 17.6% and 301.4% compared to the as-sintered commercially pure titanium (CP-Ti) properties and far exceed the ASTM standard B381 for Grade 4 wrought Ti alloy (550 MPa and 15%) with the same O content. This work offers a novel method to develop high-strength and superior-ductility Ti materials from much more affordable Ti powder.

Unveil self-plasticized polyvinyl alcohol derived customizable patterned photosensitive resin films

Since the invention of movable type in ancient times, relief printing, often called flexographic printing, has been performed to mass-produce artifacts ranging from decorative graphics to printed media. Polyvinyl alcohol (PVA) substrates are soluble in water with low toxicity but have the disadvantages of poor elasticity and brittleness. Thus, this study aims to improve the resilience of water-developable photopolymer resin plates by modifying PVA with allyl polyoxyethylene ether (APEG) in solution polymerization. In order to better control polymerization, the reactivity ratios of both were investigated (rVAC = 0.32 and rAPEG = 0.12). Impressively, the lowest glass transition temperature (Tg) of the modified PVA (m-PVA) can reach −49.98 °C, which is significantly lower than that of PVA0599 (degree of polymerization = 500, degree of hydrolysis = 99 mol%) (Tg = 52.02 °C). Moreover, this resultant m-PVA exhibits superior elongation at break (443.23 ± 37.65 %) than PVA0599 (9.98 ± 3.95 %). It is found that photopolymer plates of m-PVA have maintained a 98 % elasticity recovery rate even after water washing. Due to the better elasticity of m-PVA, the clarity of the photopolymer plate is higher than that of traditional PVA. This water-soluble self-plasticized m-PVA is expected to be applied to the fine flexographic printing industry, such as electronic devices, components, and sensors.

Microstructural design for achieving high performances in Ti-V-Al lightweight shape memory alloys by optimizing Zr content

In the present study, the quaternary Zr element was introduced to replace Ti in Ti-V-Al based shape memory alloys. The addition of Zr element resulted in the microstructural features of Ti-V-Al based shape memory alloys, such as the phase evolution of αˊˊ → β, the precipitation of C14-type Laves phase, reduction of grain size etc. Moreover, the two-stage martensitic transformation corresponding to ω → β and αˊˊ → β transformation gradually evolved into single ω → β martensitic transformation during heating process in Ti-V-Al based shape memory alloys, as Zr content was increased from 0.5 at.% to 5.0 at.%, which was firstly reported in Ti-V-Al based shape memory alloys. Meanwhile, the martensitic transformation temperatures of Ti-V-Al based shape memory alloys were decreased with Zr increasing. By optimizing Zr content, the highest yield strength and largest microhardness can be gained in Ti-V-Al based shape memory alloy with controlling 5.0 at.% Zr, as a result of solution strengthening, grain refinement and precipitation strengthening. Besides, the moderate Zr content caused the precipitation of C14-type Laves phase and formed the quasi-continuous network structure, which contributed to the superior elongation. And the perfect fracture ductility with an elongation of 40% in the present Ti-V-Al based shape memory alloys with 3.0 at.% Zr was significantly larger than that the other reported Ti-V-Al based shape memory alloys. Moreover, the superior strain recovery characteristics with a fully recoverable strain of 4% can be achieved in Ti-V-Al based shape memory alloys through controlling 3.0 at.% Zr.

Multifunctional Flexible Sensor Based on PU-TA@MXene Janus Architecture for Selective Direction Recognition.

Multifunctional selectivity and mechanical properties are always a focus of attention in the field of flexible sensors. In particular, the construction of biomimetic architecture for sensing materials can endow the fabricated sensors with intrinsic response features and extra-derived functions. Here, inspired by the asymmetric structural features of human skin, a novel tannic acid (TA)-modified MXene-polyurethane film with a bionic Janus architecture is proposed, which is prepared by gravity-driven self-assembly for the gradient dispersion of 2D TA@MXene nanosheets into a PU network. This obtained film reveals strong mechanical properties of a superior elongation at a break of 2056.67% and an ultimate tensile strength of 50.78MPa with self-healing performance. Moreover, the Janus architecture can lead to a selective multifunctional response of flexible sensors to directional bending, pressure, and stretching. Combined with a machine learning module, the sensor is endowed with high recognition rates for force detection (96.1%). Meanwhile, direction identification in rescue operations and human movement monitoring can be realized by this sensor. This work offers essential research value and practical significance for the material structures, mechanical properties, and application platforms of flexible sensors.

Preheating Influence on the Precipitation Microstructure, Mechanical and Corrosive Properties of Additively Built Al-Cu-Li Alloy Contrasted with Conventional (T83) Alloy.

In this paper, the high strength and lightweight Al-Cu-Li alloy (AA2099) is considered in as-built and preheated conditions (440 °C, 460 °C, 480 °C, 500 °C, and 520 °C). The purpose of this study is to investigate the influence of laser powder bed fusion (LPBF) in situ preheating on precipitation microstructure, mechanical and corrosive properties of LPBF-printed AA2099 alloy compared to the conventionally processed and heat-treated (T83) alloy. It is shown that precipitations evolve with increasing preheating temperatures from predominantly globular Cu-rich phases at lower temperatures (as-built, 440 °C) to more plate and rod-like precipitates (460 °C, 480 °C, 500 °C and 520 °C). Attendant increase with increasing preheating temperatures are the amount of low melting Cu-rich phases and precipitation-free zones (PFZ). Hardness of preheated LPBF samples peaks at 480 °C (93.6 HV0.1), and declines afterwards, although inferior to the T83 alloy (168.6 HV0.1). Preheated sample (500 °C) shows superior elongation (14.1%) compared to the T83 (11.3%) but falls short in tensile and yield strength properties. Potentiodynamic polarization results also show that increasing preheating temperature increases the corrosion current density (Icorr) and corrosion rate. Indicated by the lower oxide resistance (Rox), the Cu-rich phases compromise the integrity of the oxide layer.

Strong, Tough, and Anti-Swelling Supramolecular Conductive Hydrogels for Amphibious Motion Sensors.

Conductive polymer hydrogels (CPHs) are widely employed in emerging flexible electronic devices because they possess both the electrical conductivity of conductors and the mechanical properties of hydrogels. However, the poor compatibility between conductive polymers and the hydrogel matrix, as well as the swelling behavior in humid environments, greatly compromises the mechanical and electrical properties of CPHs, limiting their applications in wearable electronic devices. Herein, a supramolecular strategy to develop a strong and tough CPH with excellent anti-swelling properties by incorporating hydrogen, coordination bonds, and cation-π interactions between a rigid conducting polymer and a soft hydrogel matrix is reported. Benefiting from the effective interactions between the polymer networks, the obtained supramolecular hydrogel has homogeneous structural integrity, exhibiting remarkable tensile strength (1.63MPa), superior elongation at break (453%), and remarkable toughness (5.5MJ m-3 ). As a strain sensor, the hydrogel possesses high electrical conductivity (2.16S m-1 ), a wide strain linear detection range (0-400%), and excellent sensitivity (gauge factor = 4.1), sufficient to monitor human activities with different strain windows. Furthermore, this hydrogel with high swelling resistance has been successfully applied to underwater sensors for monitoring frog swimming and underwater communication. These results reveal new possibilities for amphibious applications of wearable sensors.

Superior combined strength and elongation by conducting elevated temperature constrained groove pressing on Al–Mg–Mn sheets

Al 5083 alloy has widely been employed in marine and offshore engineering as well as production of various types of superplastically formed parts in aerospace and automotive industries. The constrained groove pressing (CGP) is also one of important sheet severe plastic deformation (SPD) technique. In this study, The CGP process has been performed on Al 5083 sheets at an elevated temperature and up to three cycles. Complementary experiments, namely metallography, precipitation evolution, hardness and tensile tests as well as fractography were conducted for various deformed and undeformed sheets. The 1-passed workpiece represented the minimum average grain size (AGS) 8 μm due to huge strain induction. By computing the inhomogeneity factor (IF), it was also found that the 2-passed sample was the most inhomogeneous worksheet with an IF of 6.3. By performing three CGP cycles, superior elongation of 56.2% combined with UTS of 309 MPa were achieved for the 3-passed sample, making this workpiece very suitable for conducting any subsequent metal forming process. This was mainly due to the precipitation evolutions of Al6(Fe,Mn) and Al3Mg2 particles. Moreover, fractography of various specimens showed that by performing greater number of CGP cycles, the fracture mechanisms changed to a ductile mode due to creation of tiny and deep dimples.

Effect of rare earth element Er on the microstructure and properties of highly alloyed Al-Zn-Mg-Cu-Zr-Ti alloy

By using standard melting casting, homogenization, extrusion, solid solution, and T6 aging, an Al-11Zn-3.1Mg-1.2Cu-0.2Zr-0.16Ti alloy was created, and the microstructure and mechanical properties of the alloy with various Er contents were investigated. The inclusion of Er promoted the increase in the number density and volume fraction of L12-Al3(Er, Zr) in the alloy, which greatly reduced the alloy's tendency to recrystallize, raised the internal dislocation density, and helped the alloy achieve grain refinement. To a certain extent, a moderate amount of Er added to the alloy may have helped the precipitation and phase transformation of precipitates. When the Er concentration rose from 0.15 to 0.45 wt.%, the refining effect and the density of L12-Al3(Er, Zr) were less influenced, but excessive Er interacted with other elements to form coarse intermetallic compounds, leading to the deterioration of mechanical properties. The yield strength (YS) and ultimate tensile strength (UTS) of the alloy grew first and then declined and flattened as the Er content increased from 0 to 0.45 wt.%, according to the mechanical properties test. All alloys with Er microalloying had superior elongation due to the decrease of number of high-angle grain boundary (HAGB). The optimal mechanical properties were shown in the 0.15 wt.% Er alloy, with a YS of 771.7 MPa, a UTS of 785.9 MPa, and an elongation of 9.5%.

Inclusive anisotropy and texture analyses of AZ91 Mg sheets subjected to various passes of elevated-temperature constrained groove pressing

Constrained groove pressing (CGP) is a kind of sheet severe plastic deformation method suitable for enhancing the strengths of light alloys for various applications such as aerospace and automotive industries. In this research, the annealed AZ91 Mg alloy sheets were subjected to three CGP cycles at 300°C. Subsequently, optical microscopy, scanning electron microscopy, x-ray diffraction, and tensile tests for various directions were performed. Initially, there was a basal texture with a maximum intensity of 3.4 multiple random distribution and several β-Mg17Al12 particles as the second phase in the annealed sheet. As an important achievement of employing the CGP operation, the 1-passed sample represented a superior elongation of 35.7%, maximum yield strength of 141.0 MPa, and maximum ultimate tensile strength of 231.0 MPa in the rolling direction. These were mainly due to, the grain refinement, enhancing the fiber texture in the transverse direction, and controlling the basal texture. However, the experimental results revealed that the basal texture during the second and third passes of the operation could not be controlled. The main preferred orientation was changed from [Formula: see text] fiber for the annealed sheet to [Formula: see text] fiber for the CGPed sheets. It is also interesting to note that based on an anisotropy analysis, the 1-passed sample was the most isotropic worksheet, making this specimen a suitable blank for secondary metal forming processes, in comparison with the other CGPed samples. Fractography also indicated that the fracture mechanism varied among ductile, brittle, and mixed modes for workpieces subjected to different passes of the process.

Modeling and concepts of the Malingue plasty compared to Z-plasty

Malingue's diamond-shaped skin plasty is a random skin plasty derived from the Z-plasty. Not widely known, this technique is an alternative to fasciectomy in Dupuytren’s disease. The main objective of the present study was to analyze the topographical and anatomical differences between Z-plasty and Malingue plasty in cadaveric and experimental models and the geometrical and mathematical differences in modeling, in order to determine the respective gains in length. The study was carried out in two steps. An anatomical step on a cadaveric model studied vascularization. The second step was based on inert models (latex gloves) and cadaveric models, to study the mechanical behavior of the flaps. Differences in gains in length were analyzed by Euclidean and non-Euclidean geometry. The Malingue plasty flaps showed greater vascular richness than in Z-plasty. The experimental cadaver and inert material models showed 50% length gain with a single Malingue plasty, versus 33.3% with Z-plasty. The gain decreased in multiple plasties: respectively, 25% and 17.5% with double plasty and 20% and 16.7% with triple plasty. The analysis of Euclidean plane geometry did not explain these results, whereas 3D analysis on non-Euclidean geometry can explain a superior elongation effect in the Malingue plasty. The Malingue plasty could be an interesting option when significant lengthening is required, especially when Z-plasty would be insufficient.

High Cycle Fatigue and Very High Cycle Fatigue of Orthorhombic (O + α&lt;sub&gt;2&lt;/sub&gt;)-Type Ti–27.5Nb–13Al Alloy with and without B and Fatigue Striation Analysis in Comparison with (α + β)-Type Titanium Alloys

The lightweight and high strength Ti–27.5Al–13Nb intermetallic alloy, based on the orthorhombic Ti2AlNb phase (O phase) and the α2 phase incorporated, was previously developed by the authors. This alloy would seem to have good potential for applications where fatigue behavior is a main concern, such as automobile and aircraft engine parts. The minor addition of boron (B) is known to refine the ingot grain size and thus to improve the subsequent mechanical properties. For these reasons, the high cycle fatigue (HCF) and very high cycle fatigue (VHCF) properties of B-free and 0.1 pct B-modified Ti–27.5Al–13Nb alloy were examined in the present study. HCF tests were performed at room temperature (RT) in tension-tension mode at an R of 0.1 and a frequency of 10 Hz, while VHCF tests were performed using an ultrasonic resonance fatigue test machine at an R of −1 and a frequency of 20 kHz. In both fatigue tests, hourglass-shaped specimens were used. With the addition of 0.1 pct B, the prior B2 grain size of an ingot was reduced drastically, from 600∼1000 µm for the B-free alloy to 100∼250 µm. The 0.1 pct B-modified Ti–27.5Al–13Nb alloy with a duplex microstructure consisting of a globular α2 phase and a lamellar microstructure exhibited superior elongation of 6.1 pct at RT. The HCF curve for this alloy with a duplex microstructure was almost the same as that for a Ti–6Al–4V alloy with a fully lamellar microstructure. Although prolonged fatigue life was previously reported in the HCF region in the 0.1 pct B-modified Ti–6Al–4V alloy, the addition of 0.1 pct B to the Ti–27.5Al–13Nb, Ti–6Al–4V and Ti–4Al–2.5V–1.5Fe alloys had no such effect in the VHCF region. VHCF strength for a lamellar microstructure was ranked in the order of Ti–4Al–2.5V–1.5Fe, Ti–6Al–4V and Ti–27.5Al–13Nb from the highest. Well-defined striations were observed at the propagation stage area of the fatigue fracture surface of B-free Ti–27.5Al–13Nb, and the measured striation spacing kept a constant of 0.29 µm through the propagation distance of 300 µm. The calculation based on this observation showed that the fatigue life spent in the propagation stage was very short and thus almost 100 pct of HCF life was thought to be spent in the fatigue initiation stage. For the B-free Ti–6Al–4V alloy with an equiaxed microstructure, the striation spacing increased from 0.06 µm to 4 µm as the fatigue crack propagated for a distance of 1,000 µm. Calculation based on the striation spacing revealed that, similar to the case with the Ti–27.5Al–13Nb alloy, the fatigue initiation stage consumed almost 100 pct of fatigue life regardless of the B addition.

Ultrahigh-capacity epitaxial deposition of planar Zn flakes enabled by amino-rich adhesive hydrogel electrolytes for durable low-temperature zinc batteries

Aqueous zinc batteries (AZBs) show promising applications in large-scale energy storage and wearable devices, but suffer from poor reversibility of Zn anodes due to zinc dendrites and possible side reactions. We prepared amino-enriched polypyrrole modified polyacrylamide hydrogel for using as electrolytes in AZBs. The proposed electrolyte exhibits excellent adhesiveness of 19.8 kPa at room temperature (RT), high Zn2+ ion conductivity of 17.6 mS cm−1 at -20 °C, superior elongation of over 1000%, and fast self-healing in ten seconds at -30 °C. The proposed electrolyte enables unique epitaxial Zn deposition with ultra-high areal capacity up to 100 mAh cm−2 under 2 mA cm−2 in symmetric zinc cells. Importantly, this electrolyte assembled quasi-solid-state Zn/V2O5 batteries deliver a high capacity of 200 mAh g−1 at 1 A g−1 and a high capacity retention of 96.4% after 2000 cycles at -20 °C, demonstrating the promising features of the hydrogel electrolytes in high-performance AZBs.