Alloy Fibers Research Articles

Optimizing superelastic shape-memory alloy fibers for enhancing the pullout performance in engineered cementitious composites

Abstract This study explores the effect of integrated superelastic shape-memory alloy fibers (SMAFs) on the mechanical performance of engineered cementitious composites (ECCs). Various SMAF configurations – linear-shaped SMAFs (LS-SMAFs), hook-shaped SMAFs (HS-SMAFs), and indented-shaped SMAFs (IS-SMAFs) – with diameters of 0.8 and 1.0 mm were incorporated into ECC matrices, and surface texturization was achieved through abrasive paper treatment. Their mechanical properties were assessed through single fiber pullout tests on ECC mixtures containing 1.5 and 2.0% polyvinyl alcohol (PVA), subjected to both monotonic and cyclic loading conditions. Qualitative analysis, employing scanning electron microscopy, demonstrated that the IS-SMAF configuration provided superior mechanical interlocking and fiber–matrix adhesion, with a distinct flag shape observed during tensile testing. Quantitative data indicated that IS-SMAFs significantly improved the tensile strength and pullout resistance, with slip distances of ≥5 mm and average pullout loads ranging from 263 to 403 N. LS-SMAFs demonstrated better performance compared to HS-SMAFs and LS-SMAFs in terms of tensile and pullout characteristics. Additionally, ECCs with increased PVA content exhibited enhanced withdrawal performance. Thermogravimetry analysis and X-ray diffraction provided insights into the high-temperature stability and crystalline structure of the composites. These results underscore the effectiveness of IS-SMAFs in enhancing ECC properties, offering significant implications for the development and optimization of high-performance composite materials in civil engineering applications.

Synergistic effects of SMA fibers and fly ash on the material characterization of recycled aggregate concrete

This study focuses on improving the material characterization of Recycled Aggregate Concrete (RAC) while minimizing its environmental impact. It explores the interaction between Shape Memory Alloy (SMA) fibers and fly ash (FA) in RAC. Comprehensive microstructural and mineralogical analyses were conducted using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD), along with thermal assessments via Thermogravimetric Analysis (TGA) and Differential Thermogravimetry (DTG). SEM images consistently revealed hydration products, including calcium hydroxide and ettringite, across all specimens. The results indicate that incorporating SMA fibers significantly enhances FA-containing RAC by improving mechanical strength, thermal regulation, matrix densification, and crack control, effectively addressing the inherent weaknesses of recycled aggregates.

Nitric acid-modified amorphous alloy fiber and its effects on mechanical properties of ultra-high performance concrete (UHPC)

The traditional steel fiber UHPC has the phenomenon of low strength and poor durability, which can not give full play to the practical value of UHPC. Nevertheless, amorphous alloy fibres possess notable strength, flexibility and corrosion resistance. The incorporation of amorphous alloy fibres into ultra-high performance concrete (UHPC) has been demonstrated to enhance the strength and toughness of UHPC. However, the surface of amorphous alloy fibres is characterised by a smooth and hydrophobic quality, which presents a challenge in terms of the interface bond with the cement matrix. In order to address this issue, three concentrations of nitric acid (HNO3, 2 mol/L, 4 mol/L and 6 mol/L) were employed to modify the surface of amorphous alloy fibres, and then the amorphous alloy fibres were incorporated into the cement matrix for fiber pull-out test, compression, flexural strength and impact testing. The changes in the physical and chemical properties of the amorphous alloy fibres before and after modification were analysed, and the effects on the interface bond strength and dynamic and static mechanical properties of UHPC were studied by means of SEM. The results demonstrate that the adhesion strength of the modified amorphous alloy fibre with 4 mol/L HNO3 is the most robust, with an increase of 18.7 % in compressive strength, 13.8 % in flexural strength, and 5.4 % in impact resistance. The method has been demonstrated to be effective in strengthening and toughening the cement matrix with HNO3-modified amorphous alloy fibres.

Ultrasound-assisted rapid growth of chemically bonded bifunctional mesoporous covalent organic framework submicrospheres on a nickel-chromium alloy support for efficient solid-phase microextraction of bisphenols from water and milk samples

A layer-by-layer chemical bonding strategy was developed for fast in situ growth of bifunctional mesoporous covalent organic framework submicrospheres (COF SMSs) on the nickel-chromium alloy (Ni-Cr) fiber substrate via the ultrasound-assisted Schiff-base reaction for the first time. COF SMSs showed well-defined morphology, extraordinary high surface area (1211 m2·g−1) and narrow mesopore (2.50 nm) as well as excellent stability. Furthermore, the resulting Ni-Cr fiber presented outstanding adsorption capability and improved selectivity for bisphenols (BPs). Consequently, an attractive SPME-HPLC-UV approach with the Ni-Cr@Ni-Cr LDHs NSs@COF SMSs fiber was proposed for rapid preconcentration and sensitive determination of BPs. By optimizing adsorption parameters, the SPME-HPLC-UV method presented good linearity for five BPs in the ranges of 0.02–200 ng·mL−1 with coefficients of determination (R2) higher than 0.999. Limits of detection and limits of quantitation were obtained from 0.003 ng·mL−1 to 0.006 ng·mL−1 and from 0.010 to 0.019 ng·mL−1, respectively. Moreover, the intra-day and inter-day precision expressed as relative standard deviations (RSDs) was 1.57–3.52 % and 2.65–4.38 % for the proposed method with a single fiber, respectively. RSDs of the proposed method with different duplicate fibers were 3.25–6.72 %. The proposed SPME-HPLC-UV method was available for efficient preconcentration and sensitive detection of five BPs from real water and milk samples. The relative recoveries at three spiking levels of BPs were achieved in the range of 80.00–118.8 % with RSDs below 7.81 %. In addition, the prepared fiber still exhibited satisfactory adsorption performance after 120 adsorption-desorption cycles.

Reversible Electrochemical Swelling of Straight Carbon Nanotube Yarns for High-Performance Linear Actuation.

Coiled artificial muscle yarns outperform their straight counterparts in contractile strokes. However, challenges persist in the fabrication complexity and the susceptibility of the coiled yarns to becoming stuck by surrounding objects during contraction and recovery. Additionally, torsional stability remains a concern. In this study, it is reported that straight carbon nanotube (CNT) yarns when driven by a low-voltage electrochemical approach, can achieve a contractile stroke that surpasses even NiTi shape memory alloy fibers. The key lies in the suitable match between a yarn consisting of randomly aligned CNTs and the reversible and substantial electrochemical swelling induced by solvated ions. Wrinkled structures are formed on the surface of the CNT yarn to adapt to the swelling process. This not only assures torsional stability but also enhances the surface area for improved electrode-electrolyte interaction during electrochemical actuation. Remarkably, the CNT artificial muscle yarn generates a contractile stroke of 8.8% and an isometric stress of 7.5 MPa under 2.5 V actuation voltages, demonstrating its potential for applications requiring low energy consumption while maintaining high operational efficiency. This study highlights the crucial impact of CNT orientation on the effectiveness of electrochemically-driven artificial muscles, signaling new possibilities in smart material and biomechanical system development.

Mechanical Properties of Ultra-High-Performance Concrete with Amorphous Alloy Fiber: Surface Modification by Silane Coupling Agent KH-550.

Amorphous alloy fiber has the advantages of high tensile strength and high corrosion resistance compared with steel fiber, but its interfacial bonding with cement matrix is poor and requires surface modification treatment. In this study, the surface modification of amorphous alloy fiber was carried out by using silane coupling agent KH-550 solution, and its effect on the mechanical properties of ultra-high-performance concrete was investigated. The results showed that the amorphous alloy fibers modified with 15% concentration silane coupling agent KH-550 solution can effectively improve the mechanical properties of the ultra-high-performance concrete, where the interfacial bond strength with the cement matrix reached 3.29 MPa and the roughness reached 3.85. The compressive strength, flexural strength, tensile strength, and peak stress of the ultra-high-performance concrete mixed with modified amorphous alloy fibers could reach up to 133.6 MPa, 25.5 MPa, 8.32 MPa, and 114.26 MPa, respectively, which were 2.9%, 6.3%, 10.9%, and 4.3% higher than those of the ultra-high-performance concrete with unmodified amorphous alloy fibers. As the surface of the fiber was modified, its properties changed and the bonding effect with the cement matrix was better, which in turn improved the mechanical properties of the ultra-high-performance concrete.

Twinning and 9R Phase Transition Mediated Extraordinary Cold-drawn Deformability in NiCoCrFeMo High-Entropy Alloy.

The production and application of materials are evolving towards the low-dimensional micro-nano scale. Nevertheless, the fabrication of micron-scale alloy fibers remains a challenge. Herein, a novel Ni-Co-Cr-Fe-Mo high-entropy alloy (HEA) fiber with a cold-drawn reduction rate of 99.9995% and a strain (ɛ) of 12.19 is presented without requiring intermediate annealing. The exceptional deformation strain of 11.62 within the fiber leads to extraordinary tensile strengths of 2.8GPa at room temperature and 3.6GPa at 123K. The in-depth investigation of the microstructure of fibers has revealed the cold drawing deformation mechanisms mediated by the synergistic effects of plane defects. Specifically, various geometrically necessary dislocation interfaces, such as dislocation walls and microbands, along with deformation twins and long-period 9R structures, form in response to external stress when ɛ≤2.7. As the strain increases, the saturated layered structure emerges and progressively evolves into a 3D equiaxed crystal. Moreover, the formation and evolution of the 9R structure (i.e., the migration of incoherent twin boundaries), coupled with the interaction of partial dislocations and the role of deformation twins, are crucial factors determining the fiber's plastic response. This work provides a novel approach to discovering new high-strength metallic fibers with excellent deformability through plane defects engineering.

Design of self-healing materials for the integration of structural health monitoring (SHM^2)

Integration of the complementary fields of structural health monitoring in self-healing materials (SHM2) has the potential to transform the traditional engineering concepts of fail safe and damaged tolerant design. Structural health monitoring seeks to embed and automate sensing capabilities within structures to determine their state and to detect degradation or damage. Once degradation or damage is detected, additional decisions and potential action are required. Reducing operational envelopes can prevent further damage accumulation or catastrophic failure or repairs can be performed to correct the degradation. Typical repair requires active involvement of personnel and potentially down time. Self-healing materials seek to avoid maintenance needs and down time through the creation of structures and materials with an imbued capability to repair damage. Together SHM^ 2 has the potential to create a closed loop where damage is detected using embedded sensors and automated analysis that can then initiate self-healing. The highly structured and controlled nature of self-healing materials presents an opportunity to design structures that additionally support health monitoring capabilities. This paper presents recent research and results informing the design of shape memory alloy (SMA) fiber reinforced metal matrix composites (MMCs) to optimize self-healing capabilities and structural health monitoring (SHM^2). Fiber pull tests were performed to analyze the strength of the interface between the SMA fibers and matrix allowing for sizing to complement both composite design and healing capabilities. Analysis was performed to understand complex failure mechanisms occurring at the interface between detwinning shape memory alloys and the metal matrix. And novel composite design was performed to support both the self-healing and damage detection capabilities of the material structure.

Improving the Mechanical Properties of Concrete Mixtures by Shape Memory Alloy Fibers and Silica Fume

Improving the Mechanical Properties of Concrete Mixtures by Shape Memory Alloy Fibers and Silica Fume

Static and impact performance of engineered cementitious composites with hybrid graphite nano platelets modified PVA and shape memory alloy fibres

Polyvinyl alcohol (PVA) fibre has been widely adopted to produce engineered cementitious composites (ECC), the overall performance of which is highly dependent on the fibre surface characteristics. The traditional approach to improve PVA fibre bridging ability is to tailor the surrounding matrix properties. However, this common practice need to do a lot of laborious experimental works, and thus it has limited efficiency and practicality. Therefore, special surface treatments on PVA fibres are required to create synergistic interactions between fibre and surrounding matrix to retain excellent tensile ductility and better mechanical performance. This paper proposes a novel treatment method for PVA fibres using nano graphite platelets to modify the PVA fibre surface and improve the mechanical properties of PVA fibre reinforced ECC. To evaluate the effectiveness of such treatment, a systematic experimental study was performed. Firstly, static contact angle measurements, scanning electron microscopy and atomic force microscopy were employed to monitor the wettability and physical changes on the fibre surface. Then, the static and dynamic mechanical properties as well as microstructural characteristics of ECC with hybrid modified PVA fibres (2 vol%) and shape memory alloy (SMA) fibres (0.25 vol%, 0.50 vol% and 1 vol%) were examined. The results indicate that the graphite nanoplatelets treated PVA fibres (GPVA) exhibit high hydrophobicity and surface roughness providing steady-state crack propagation, which is a necessary condition to ensure multiple cracking and improving the higher fibre bridging complementary energy. This is evidenced by significantly densified the transition zone between the graphite treated PVA fibres and the matrix, and improved the flexural tensile strength and the toughness. The calculated surface roughness of 28.86 μm and lots of peaks and valleys on the 3D topographical micrographs of the cracking faces confirmed that 1 SMA-2 GPVA specimen efficiently participated in transferring stress through the composite, leading to a greater vertical impact reaction force. Finally, the structure-property relation for flexural versus fracture behaviour and the effectiveness of SMA fibres on the crack-healing feature of the composites were studied by using digitized fractal analysis and through the heat treatment. The disseminated fracture energy (Ws/Gf) value reached 130 and the crack sizes the crack size decreased by 34 %, which were much better than that of the reference composites. The nano treatment of PVA fibres in ECC provides an innovative and sustainable solution for engineering structures with requirement of high tensile ductility and high impact resistance, e.g., military infrastructure and industrial floors.

A Superb Iron-Based Glassy-Crystal Alloy Fiber as an Ultrafast and Stable Catalyst for Advanced Oxidation

A Superb Iron-Based Glassy-Crystal Alloy Fiber as an Ultrafast and Stable Catalyst for Advanced Oxidation

Axial crushing behavior of CoFeSiB amorphous alloy fiber/epoxy composites under compression condition

AbstractIn this article, the axial crushing behavior of CoFeSiB amorphous alloy fiber reinforced epoxy composites (AAFRCs) with different fiber volume fractions (30%, 40%, 50%, and 60%), fiber orientations (0°, 15°, and 30°), and fiber shapes (straight and sinusoidal) were investigated under compression condition. The results show that energy absorption (EA) and crush force efficiency (CFE) of the composites show a tendency to increase and then decrease with the increase of fiber volume fractions. The appropriate increase in fiber orientation can improve the EA and the CFE of the composites. The EA of reinforced composites with sinusoidal fiber is 66% higher than that of the ones with straight fiber. Three damage modes were identified by combining the damage process images corresponding to the compressive load–displacement curves and the morphologies of the crushed composites. The EA mechanism of the new composites was analyzed by observing the damage process of the AAFRCs.Highlights A novel CoFeSiB amorphous alloy fiber reinforced epoxy composites. The increase in fiber orientation improves the energy absorption and the crush force efficiency of the composites. The energy absorption of reinforced composites with sinusoidal fiber is higher than that of the composites with straight fiber. Three damage modes were identified: compression damage, axial bending and transverse shear.

Vibration analysis of active composite structures embedded with long and short shape memory alloy (SMA) fibers

The shape memory effect (SME) is a source of internal compressive stresses that modify the vibration behavior of shape memory alloy (SMA) embedded composite structures. Generally, long fibers are used due to their suitability for activating SMA using resistive heating. Longer SMA fibers embedded in composite structures have their limitations in design and manufacturing. Minimal research work has been done on tuning the vibration behavior of composite structures embedded with short SMA fibers. In this research paper, an analytical model for evaluating the natural frequencies of an SMA embedded composite beam has been proposed. Effects of various design parameters for long (continuous) and short (discontinuous) SMA fibers embedded in composites have been investigated. It was observed that short SMA fibers with a higher aspect ratio can tune their frequencies similarly to long SMA fiber composites and are more effective in thicker beams. Matrix material with negative coefficient thermal expansion is more suitable for embedding SMA for modifying natural frequency in active mode.

Recovery stress, bond resistance, and stiffness to slip of crimped SMA fibers with considering geometric variation

Bond resistance is critical for reinforcing fibers in cementitious materials. Recently, crimped shape memory alloy fibers (SMA) have been raised as candidates for providing abundant benefits such as improved strength, enhanced durability, and crack closing. This study aimed to examine the influence of wave-depth and wave-length of crimped SMA fibers on their bond behavior. The crimped fibers in this study were categorized in four groups based on the wave-length. Each group had four types of fibers that considered the ratio of wave-depth to wave-length (DLR). Thus, a total of sixteen types of fibers were prepared with variations in wave-length and wave-depth. The tensile test used bare crimped SMA fibers, while the pullout tests used half dog-bone specimens. After the tests, the finite element model was used to evaluate the interaction parameters that were difficult to measure in the experience test. The results showed that the fibers with the smallest wave-length showed the largest maximum bond resistance in the same dept-to-length ratio (DLR) group, and that values decreased with an increasing wave-length. In addition, the smallest wave-length fibers demonstrated the most effective stiffness. Furthermore, the finite element analysis discovered that the geometric friction coefficients of the crimped SMA fibers were affected significantly by the geometric variation. The longer wave-length fiber revealed the larger estimated frictional coefficient.

Parameter influence analysis of stochastic resonance and stochastic P-bifurcation for the shape-memory alloy laminate

This paper investigates the transverse vibration of an axially moving shape-memory alloy (SMA) fiber hybrid laminations under the combined action of transverse harmonic excitation and stochastic disturbance. Considering the shape memory alloy (SMA) fiber volume fraction random field, the kinetic energy and strain potential energy of SMA laminates are solved, and the axial motion equation of SMA laminates is derived according to Hamilton principle, a non-dimensional differential equation of the transverse vibration of the axially moving SMA laminated plates is obtained by adopting the Galerkin integral method. Considering the volume-fraction stochastic field, the stochastic natural vibration of a SMA laminate is analyzed. Considering the stochastic resonance of the SMA laminate under the action of Gaussian white noise and harmonic excitation, the effects of geometric parameters, physical parameters of materials, and temperature on the stochastic resonance behavior of the SMA laminate is analyzed. Finally, the effect of the stochastic P-bifurcation phenomenon of the parameters on the steady-state response of the SMA laminate is analyzed.

Plastic deformation and strengthening mechanism in CoNiV medium-entropy alloy fiber

High/medium-entropy alloys (H/MEAs) are regarded as a potentially viable alternative to conventional metallic fibers for the production of ductile, high-strength fibers, to resolve the inherent trade-off between strength and ductility. The present study involved the cold drawing technique to produce a CoNiV MEA fiber measuring 300 μm in diameter with a length of more than 3 m. The mechanical properties of the FCC matrix can be improved through the inclusion of an appropriate amount of the κ phase via the optimized thermal treatment process. In addition to a yield strength of 1681 MPa and a well-coordinated elongation of 13.4 %, the ideal CoNiV fiber demonstrated a substantial ultimate tensile strength of 1932 MPa. Further calculations revealed that the κ phase, which possesses a substantial Von Mises stress of approximately 2715 MPa and an area fraction of 18.2 ± 1.1 %, was observed to be a primary contributor to the strength. Deformation twins were generated in the FCC matrix as a result of the ultra-high flow stress, which provided adequate ductility. This study offers significant contributions to the understanding of the deformation mechanisms and strengthening effect of the κ phase, thereby facilitating the development of high-performance metallic fibers.

Large Deformation Dynamic Characteristics of Cracked Laminated Panel and Improvement of Stiffness Using Shape Memory Alloy Fiber

Abstract This study explores the investigation of the nonlinear dynamic responses or time-dependent deflection analysis of a laminated composite shell panel integrated with a shape memory alloy (SMA), considering both undamaged and damaged set-ups. The primary focus of this research is to examine the impact of SMA incorporation on the structural behavior of the parent configuration, aimed at enhancing its structural stiffness. To ensure the validity of the proposed model, sensitivity analyses and numerical validations are presented. The mathematical framework employed in this study employs the higher-order shear deformation theory (HSDT), which offers enhanced accuracy in capturing the intricate behaviors of these shell panels. The dynamic responses are obtained using the Newmark average acceleration method. Numerical simulations are carried out using a dedicated MATLAB code developed in-house, allowing amplified correctness in outcomes and widespread analysis. The study thoroughly assesses a range of geometric parameters and those relevant to SMA for both intact and impaired shell panels. The outcomes of the investigation reveal affirmative findings, underscoring notable improvements in structural strength and enhanced nonlinear dynamic responses through the introduction of SMA reinforcement into the composite shell panel.

Preparation and mechanisms of Cu–Ag alloy fibers with high strength and high conductivity

Cu–Ag alloy fibers are known for their excellent electrical and thermal conductivity, and are widely used in various fields, such as electronics, transportation, and processing due to their low price and simple preparation process. Nevertheless, this trade-off relation between strength and electrical conductivity of Cu–Ag alloys restricts their scope of application. In order to prepare Cu–Ag alloy fibers with high strength and high electrical conductivity, three different processes: cold drawing, surface electrodeposition and electrolytic polishing, are investigated and comprehensively utilized. By comparing the evolution of microstructure and properties in Cu–Ag alloy fibers, along with the corresponding mechanisms for strengthening and conductivity, one most suitable process path is explored. Cold-drawing is utilized to reduce the grain size, which, in turn, enhances the strength of the fibers. Meanwhile, it refines the internal grains of the alloy by shearing and deflecting each other, ultimately resulting in a fiber texture along the drawing direction. The main contributors to the strength of Cu–Ag alloy fibers are dislocation strengthening, grain boundary strengthening, and texture strengthening. The slight difference is that for electrical conductivity, dislocation and grain boundary play a crucial role. Electrodeposition of copper on the fiber surface is an effective method for improving the electrical conductivity of the fiber, which is achieved by creating a dense conductive pathway on the surface of the fiber. However, this process leads to a reduction in strength. Therefore, electrolytic polishing is subsequently used to regulate the plating thickness in order to obtain Cu–Ag alloy fiber with synchronous increase of strength and electrical conductivity.

A strategy of fabricating efficient Mg2Ni nano-catalysts in Mg-Ni-Ag fibers and their excellent hydrogen storage properties at near-room temperatures

In this study, a new strategy was utilized to fabricate Mg-based hydrogen storage fibers with uniform elemental distribution and diameters of 30–50 μm. The in-situ formation of nano-precipitates in Mg85Ni14.8Ag0.2 metallic glass fibers was visually observed at varied annealing temperatures. It indicates the metastable Mg6Ni phase is formed from an amorphous microstructure initially. Then, the needle-like Mg2Ni nanoparticles precipitate at 140–160 °C and subsequently grow into spherical shapes. This results in the formation of the fiber structure with well-distributed nano-Mg2Ni particles. The alloy fibers can absorb H2 at only 40 °C, and the activation energy for hydrogenation is lowed to be 46.9 kJ/mol. The onset desorption temperature of hydride is reduced to 220 °C due to the improved the catalytic efficiency by uniformly distributed Mg2Ni nanoparticles. The abundant interfaces, as well as the shortened distance by micropores, serve as paths for the fast diffusion of H atoms.

Investigation of flexural behavior of crimped SMA fiber-reinforced mortar beams through experimental study and mesoscale finite element modeling

This study examined the influence of the volume fraction, distribution, and orientation of crimped shape memory alloy (SMA) fibers on the flexural behavior of mortar beams through experimental tests and mesoscale finite element model (M-FEM). In the experimental testing, five groups of beams were cast, including one group with no fibers and two groups, each having a fiber volume fraction of 1.0% and 1.5%. One group of beams with a fiber volume fraction of 1.0% and 1.5% were heated to induce the shape memory effect (SME). The beams were tested by a three-point bending test to estimate their flexural capacity. In the FE analysis, the three-dimensional M-FEM of beams with different fiber volume fractions (from 0.5% to 2.0%) was developed and implemented using Python scripting and computed with the ABAQUS environment. The FE analysis results matched well with experimental data. The maximum discrepancies are 6.5% in ultimate load and 4.5% in the corresponding displacement. Furthermore, increasing SMA fiber volume fractions up to 1.5% enhanced flexural strength in SMA fiber-reinforced mortar beams, while exceeding this fraction led to negative effects due to debonding and slippage from steel reinforcement, resulting in reduced load capacity. The heated beams to induced prestressing exhibited superior performance with an ultimate load increase of over 15.0% compared to nonheated beams. Finally, this study recommends using M-FEM to investigate the SMA fiber’s reinforced structures.