The promising tungsten bronze-structured BaBiNb5O15 compound suffers from critical drawbacks, primarily its lower oxygen ion conductivity, which prevent its applications in the modern clean energy devices. This study investigates the electrical properties of BaBiNb5-xGaxO15-delta (BBNG) samples prepared by Ga3+ ion acceptor doping. The effects of Ga3+ doping on the structural, microstructural, and electrical conductivity properties of the material were systematically analyzed. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses confirmed the successful incorporation of Ga3+ ions into the lattice, accompanied by the grain refinement. Electrochemical impedance spectroscopy and dielectric modulus analysis further demonstrated that increasing Ga3+ ion doping concentration (from x = 0 to x = 0.075) enhanced bulk conductivity at 773 K while reducing the relaxation activation energy. However, when the doping level exceeded x = 0.075 (e.g., x = 0.1 and x = 0.3), both bulk conductivity and activation energy exhibited inverse trends, with conductivity declining and relaxation activation energy rising. At the optimal doping level of x = 0.075, the bulk conductivity at 773 K increases to 1.2 & times; 10-4 S/cm, 4.2 times that of pure BBN compound, while the relaxation activation energy decreases to 0.37 eV. The dielectric modulus relaxation spectra revealed that the BaBiNb4.925Ga0.075O15-delta (x = 0.075) sample showed a significantly shortened relaxation time tau relative to other doping concentrations, with the relaxation peak shifting toward higher frequencies. This shift indicates markedly enhanced oxygen ion mobility. The higher concentration and mobility of oxygen vacancies thereby yield higher oxygen ion conductivity in the BaBiNb4.925Ga0.075O15-delta (x = 0.075) sample. This study establishes the structure-activity relationship between Ga3+ ion doping concentration and barium bismuth oxide (BBN) conductivity, providing experimental insights and optimization strategies for developing high-performance oxygen ion conductors.

Due to the various excellently functional properties, BaBiNb5O15 (BBN) ceramic with the tetragonal tungsten bronze typed structure possesses widely potential in applications of optical anti-counterfeiting and optical information storage areas. In this work, this study significantly enhances the photochromic properties of BBN ceramic was significantly enhanced through Mo6+ ions donor doping. BaBiNb5-xMoxO15 (x = 0, 0.05, 0.1, 0.5) samples were prepared via solid-state method. Results demonstrate that the photochromic properties of BaBiNb5xMoxO15 samples are improved at beginning and then decreased with the increase of Mo-doped content. The BaBiNb4.95Mo0.05O15 sample, prepared with a dopant level of 0.05, exhibits a significantly enhancement about photochromic contrast (Delta Rdec) of about 29 % at 540 nm, versus 17 % for undoped BBN sample at 478 nm, and shows a response time less than 1 s. Judging from the thermoluminescence (TL) spectroscopy analysis, donor doping with Mo6+ ions suppresses oxygen vacancies with the deep traps while simultaneously introducing new effective color centers, which accounts for the enhanced photochromic properties observed in the BBN-0.05Mo sample. After 9 cycles of alternating irradiated and thermal treatments, no significant change was observed in the photochromic contrast values, which demonstrates the excellent reversibility and stability of the BaBiNb5xMoxO15 (x = 0, 0.05, 0.1, 0.5) samples. These findings are effective for improving the photochromic properties of BBN-based ceramics and provide valuable guidance for future material design and applications.

Na0.5Bi0.5TiO3-based oxide ion conductors exhibit significant potential for applications in intermediate-temperature solid oxide fuel cells. The electrical performance of the material was enhanced by doping with Cu2+ ions. Na0.51Bi0.49Ti1-xCuxO3-δ (x = 0, 0.005, 0.01, 0.02) samples were synthesized via the conventional solid-state reaction method to investigate their electrical properties and oxygen relaxation behavior. With increasing Cu2+ ion doping content, the bulk conductivity of Na0.51Bi0.49Ti1-xCuxO3-δ samples initially rises, reaching a peak at 1 mol

Cu-based shape memory alloys are an important class of smart materials whose multifunctional properties are closely related to their unique microstructure. Therefore, it is of great crucial to thoroughly elucidate the law of dynamic microstructure evolution of the alloys. Internal friction measurement was carried out to track dynamic microstructural changes and phase transformations of the as-cast Cu-12Al-5Mn (wt.

This study presents a novel catenary-inspired 3D hybrid (CCH) lattice structure, and the corresponding lattice materials were fabricated using 3D printing technology. Finite element analysis and experiments on strut length, diameter, and catenary coefficient show that the CCH lattice materials achieve superior mechanical properties and isotropy. Remarkably, sample A1 achieves a specific energy absorption of 16.68 MJ/m3 at the same strain, which represents a 91.94% increase compared with the diamond lattice structure. Within the tested range, the mechanical strength and energy absorption of the CCH lattice materials increase with larger strut diameters and decrease with longer strut lengths and higher catenary coefficients. Lastly, the typical deformation modes are progressive layer-by-layer collapse and uniform crushing, indicating stable energy absorption behavior under loading.

As a typical tungsten bronze-type ceramic, BaBiNb5O15 (BBN) is constrained by insufficient oxygen-ion conductivity at medium and low temperatures, severely impeding its deployment in clean-energy electrochemical devices. In this study, Ga3+/Al3+ co-doping is employed to tailor the properties of BBN compounds, and a systematic investigation is conducted on the microstructural evolution and electrochemical performance of BaBiNb4.925-xGa0.075AlxO15-delta samples, with doping levels spanning from x = 0.025 to 0.075. The experimental results demonstrate that increasing Al3+ doping content effectively refines the microstructure of BBN ceramics, reducing the average grain size from 4.32 mu m to 3.32 mu m. The grain ionic conductivity varies non-monotonically with the increase of dopant concentration, and the x = 0.05 sample achieves an optimal conductivity of 1.58 & times; 10-4 S/cm at 773 K, which is 5.5 times higher than that of pristine BBN ceramics. Moreover, the optimized BaBiNb4.875Ga0.075Al0.05O15-delta ceramic exhibits the lowest relaxation activation energy of 0.31 eV, as well as the maximum concentration of mobile oxygen vacancies and the shortest ionic relaxation time among all prepared samples. The rational design of Ga3+/Al3+ co-doping can effectively regulate the lattice defect configuration of BBN, thereby greatly boosting its oxygen-ion conduction capacity. This synergistic doping strategy provides a practical and innovative approach to develop high-performance oxide-ion conductors suitable for medium and low-temperature operating conditions.

Equiatomic TiNi shape memory alloys reinforced by TiB particle are prepared via vacuum arc melting by introducing MoB powder particles with varying mass fractions. The influences of in situ reaction products on the microstructure， mechanical properties， and shape memory effect of the alloy are systematically investigated. Moreover， the mechanical properties are further optimized by multi-pass cold-rolling and subsequent annealing treatment. The experimental results indicate that the alloy exhibits optimal comprehensive mechanical properties with tensile strength increasing from 461 MPa to 522 MPa and elongation after fracture rising from 4.5% to 8.6%， when the MoB addition amount is 0.1%（mass fraction）. In addition， the alloy maintains a high shape recovery rate of 93.3% under 3% pre-compression strain.The mechanical properties of the alloy are further improved subjected to cold rolling and annealing treatment. For instance， the tensile strength and elongation after fracture respectively increase to 757 MPa and 18.8% after 5 passes of cold-rolling （75% deformation） and annealing， representing increases of 45% and 118.6% compared to the unrolled alloy. Microstructural analysis reveals that the Ti2Ni precipitate particles are severely fragmented during the rolling process， resulting in reduced particle size. Recovery and recrystallization take place in the deformation zones， with the matrix exhibiting submicron grains， nanoscale martensitic structures， and nanotwins. High-density dislocations are observed both within the matrix and surrounding the TiB particles. Finally， the improved mechanism of the comprehensive mechanical properties of the TiNi alloy is systematically discussed through the evolution of microstructure.

With the growth of the global population and increasing concern for environmental issues, the development of sustainable and eco-friendly materials has become increasingly important. Starch, as a renewable resource, is one of the most abundant polysaccharides in nature, with the advantages of good biocompatibility, high biodegradability, and low cost. Starch-based hydrogels (SBHs) have attracted widespread attention due to their unique physical and chemical properties. This article provides a comprehensive review of the latest research progress in SBHs, discussing their main characteristics, formation mechanisms, diverse applications, and future development trends. First, it outlines the biocompatibility, degradability, water absorption and retention, environmental responsiveness, and mechanical strength of SBHs. Then, it elaborates in detail on the formation mechanisms of SBHs, including physical crosslinking (hydrogen bonding, electrostatic interactions, host-guest and coordination interactions), chemical crosslinking (such as initiators, heat, light, radiation, and click reactions), and synergistic effects. Subsequently, it analyzes the applications of SBHs in cutting-edge fields such as flexible sensors, medical dressings, drug delivery, tissue engineering, soil protection, wastewater treatment, and food packaging. Finally, it summarizes the challenges in current research and provides an outlook on future development trends, emphasizing the importance of further optimizing the performance of SBHs to meet broader industrial needs and environmental protection goals. This review not only provides a systematic theoretical framework for the study of SBHs but also charts a course for their innovative applications in the field of sustainable materials, playing a significant role in advancing the continuous development of this area.

The internal friction (IF) behaviors, combined with X-ray diffraction (XRD), dilatometry, and transmission electron microscopy (TEM) analysis of the cryogenic treated and tempered M54 steel were systematically investigated. In IF-temperature curves, the peak P1 was proved to be a Snoek-Ke-Koester (SKK) relaxation peak associated with interstitial carbon atoms in martensite matrix according to its activation energy. The peak P2 and P3 were attributed to reverse martensite transformation and martensite transformation, respectively, during the thermal cycle. Based on the analysis results of IF, XRD and TEM, M2C precipitation indeed occurred during tempering, leading to final ultra-high strength and hardness of the aged M54 steel.

High speed steel T15 particle reinforced copper matrix composites were prepared using powder metallurgy. A systematic investigation was conducted into the effects on the microstructure and mechanical properties of the composites of the sintering temperature, T15 hard particle content, and particle size. The results indicate that the grain size is efficiently refined by the addition of T15 hard particles. The decrease in grain size of 10 wt% T15/Cu composite is from 6.87 mu m to 1.34 mu m at the same sintering temperature, and the grain size is proportional to both the sintering temperature and the size of hard particles. As the sintering temperature increases, the relative density and hardness of the composite gradually increase, while the yield strength initially increases and then declines. When sintered at 790 degrees C, the 10 wt% T15/Cu composite achieved a maximum yield strength of 160.1 MPa, which is 178.9 % and 30.6 % higher than that of pure copper and 10 wt% TiC/Cu composites, respectively. There are no visible cracks after compression, and a good balance of strength and toughness is achieved. Meanwhile, the primary contributions of strengthening mechanisms such as grain refinement, thermal expansion mismatch and load transfer to the mechanical properties of T15/Cu composites were analyzed. It is anticipated that this will establish a foundation for the preparation and application of high-performance copper matrix composites reinforced with metal particles.

The Cu-12Al-4Ni-1Mn-xB（x=0%，0.1%，0.2%，0.3%，mass fraction，the same below） shape memory alloys were prepared by vacuum arc melting furnace after introducing trace boron element into the alloy. The influence of boron addition on the microstructure， phase transformation， and mechanical properties of the alloy was investigated. The results show that the addition of boron significantly refines the grain size， with the grain size decreasing from hundreds of microns to （11±3.45） μm. The phase transformation temperature shifts to the high-temperature side after boron is added， indicating that the phase transformation process requires higher thermal activation energy. When the boron content is 0.2%， the microhardness of the alloy is enhanced， from （301.7±2.6）HV without adding boron element to （334.3±3.4）HV， which is attributed to grain refinement and the precipitation of hard and brittle borides. The tensile fracture strength and elongation are greatly improved， with the fracture strength increasing from （320±2.6） MPa to （788±17） MPa， and the elongation increasing from （1.44±0.05）% to （3.74±0.12）%. After solid solution annealing， the fracture strength and the elongation are both further increased to （856±10.7）MPa and （5.78±0.16）%， respectively. Analysis indicates that grain refinement strengthening， precipitation strengthening of borides， and solid solution strengthening are the main mechanisms for the improvement of mechanical properties. The fracture mode of the alloy shifts from brittle fracture to ductile fracture.

TiNi shape memory alloys have clear target demand in a variety of fields owing to their excellent struc-tural and functional properties.In this paper,focusing on B2 structural austenitic Ni-rich TiNi alloys,it is proposed to modulate the microstructure of the TiNi alloys through repeated cold rolling annealing,with an expectation to enhancing the lower mechanical strength and plastic deformation ability of the alloys.The dependence of the mechanical properties and microstructure of Ti48.9Ni50.9Zr0.2 and Ti47.9Ni51.9Zr0.2 alloys on cold rolling deformation and recrystallization annealing was systematically investigated.The tensile mechanical property tests show that the repeated cold rolling annealing can significantly enhance the overall mechanical properties of the alloys,in which the tensile strength of Ti48.9Ni50.9Zr0.2 alloy is increased from 550 MPa in the unrolled samples to 1 070 MPa after 6 passes of cold rolling annealing,and the elongation after fracture has grown from 4.9％to 10.0％.The EBSD,SEM and TEM microstructural observation reveals that the deformation and recrystallization structures of the alloy change alternately after multi-pass cold rolling and annealing,and the alloy grains are significantly refined and undergo an obvious preferred grain orientation.In addition,the basal texture of the alloy is further enhanced.The Ti2Ni and Ti3Ni4 precipitates are broken and refined during cold deformation,in which the nano-sized Ti3Ni4 pre-cipitate exhibits a favorable matching with matrix.Furthermore,stress-induced martensite as well as a large num-ber of high-density dislocations in the vicinity of the precipitation phases appear in the alloy.The mechanical pro-perties of alloys are strongly related to the microstructure,and the strengthening mechanisms can be understood by grain refinement strengthening,dislocation strengthening,precipitation strengthening and texture strengthening.

BaBiNb5O15- based oxide ion conductors have shown promise for solid fuel cell applications at medium temperatures. In this study, BaBi0.98Sr0.02Nb5-xTixO15-δ (x = 0.02, 0.04, 0.05, 0.06, 0.08) samples were prepared by the conventional solid-state synthesis with two-step sintering method. The electrical properties and oxygen relaxation behaviors of the BaBi0.98Sr0.02Nb5-xTixO15-δ samples were investigated. With increasing the Ti content, the bulk conductivity of the BaBi0.98Sr0.02Nb5-xTixO15-δ samples showed a trend of increasing first and then decreasing. When the doped Ti content reached 5 mol

The Ti50-0.5xNi50-0.5xZrx series alloys were prepared by vacuum arc melting and subsequent suctioncasting. Metallographic observation and tensile mechanical tests show that adding trace amount of Zr can reduce grain size and increase higher tensile strength and elongation, however, excessive Zr content can easily lead to the formation of brittle intermetallic compound Zr2Ni and reduce its mechanical properties.The multi-pass cold-rolling deformation and annealing treatment on Ti49.9Ni49.9Zr0.2 alloy were carried out.The results show that the tensile strength sigma(b) and the elongation delta of the Ti50-0.5xNi50-0.5xZrx alloys increase with the increase of cold-rolling deformation. Compared with the unrolled alloys, after four-passes cold-rolling deformation, the tensile strength and the elongation after fracture of the alloys increase from561 MPa, 1.14% to 768 MPa , 35.1%, respectively.Microscopic observation of SEM and TEM show that the hard Ti2Ni particles distributed along the grain boundaries during the cold rolling process are sheared and broken, resulting in a discontinuous distribution of refinement. After 700 degrees C annealing process, the deformed microstructure has recovery recrystallization, resulting in the appearance of nanocrystalline and amorphous regions. Moreover, a large number of plate-like nano-twin structures and high-density dislocations appear in the TiNi matrix with the increase of cold-rolling deformation.

CuAlMn shape memory alloys have specific target demands in various fields due to excellent thermal stability and high damping properties.However， the mechanical property of the alloy is severely weakened due to the intergranular fracture arising from the coarse grain size. To improve the mechanical properties， the Cu-11.36Al-5Mn-xY （x=0-3， mass fraction/%，the same below） alloys were prepared by using a vacuum arc melting furnace by introducing rare earth Y element. The microstructure of the as-cast CuAlMn alloy was subsequently tailored and homogenized through solid solution and aging treatment. The phase transformation， phase composition， and microstructure of the alloy were respectively characterized by DSC， XRD， metallography and SEM observations. The hardness and mechanical properties of the alloy were tested by using a microhardness tester and a universal materials testing machine. Results show that the addition of Y element effectively refines the CuAlMn alloy grain， and the grain size even reduces from several hundred μm to around 10 μm. The grain refinement is mainly associated with the increased grain nucleation areas and the inhibition of grain growth during the cooling process. Moreover， quite numbers of Y-containing precipitates with the network structure are formed and distributed along the grain boundaries. The hardness of the alloy increases with the enhancement of Y element addition， which is associated with the precipitation of a large amount of hard and brittle containing Y phases.The hardness of the solution-aged sample is higher than that of the cast sample， due to the precipitate distribution throughout the entire matrix and higher volume fraction of precipitates for the former sample.In addition， the compressive and tensile fracture strength of the alloy are significantly improved when the Y content is in the range of 0.1%-0.4%. The strengthening mechanism can be understood by grain refinement strengthening， precipitation strengthening and solution strengthening. The compressive fracture strain of the alloy reaches its maximum when the Y content is 0.4%， while the elongation after fracture exhibits the maximum value with Y content of 0.1%. The changing trend is closely related to the coupling effect between grain refinement and precipitation phases.

Because of their rapid response, high sensitivity, and excellent thermal and chemical stabilities, photochromic ceramics have attracted great potential for optical applications in anti-counterfeiting and optical information storage. However, the inferior photochromic contrast restricted the further development of photochromic ceramics. Herein, a novel modification strategy for photochromic behavior is proposed in a KSr2Nb5O15-based system. A new heterojunction band structure was established at the interfaces in ceramics by compositing with transition metal oxides and generated novel transition paths for the excited carriers. After compositing with the Nb2O5 second phase, the photochromic contrast △Rdec was almost doubled by additional color centers from the heterojunction structure. The related mechanism was confirmed by the photochromic behavior, thermoluminescence spectra and band structure features. Moreover, rapid, convenient and reversible laser bleaching behaviors was explored, and a more flexible anti-counterfeiting method was attempted through secondary laser adjustment of the photochromic pattern. This work aims to present a new modification viewpoint into photochromic ceramics by building a heterojunction structure.

A novel heterogeneous-structure (HS) twinning-induced plasticity (TWIP) steel containing alternating columnar grain (CG) and equiaxed grain (EG) domains was successfully fabricated via prestraining, partial recrystallization, and directional solidification. Compared with the traditional EG sample, the HS sample exhibited a better tensile strength–elongation combination (yield strength ≈ 263 MPa, ultimate tensile strength ≈ 573 MPa, total elongation ≈ 101.5%). The mutually constrained structure could effectively control the unique deformation modes of the EG and CG domains at different deformation stages. The HS sample exhibited stable and continuous plastic deformation owing to the timely release of localized high strain or stress, postponed plastic instability, and restrained crack propagation owing to the constrained structure. The stress relaxation was due to twinning and the effects of geometrically necessary dislocations, which accommodated deformation incompatibility. The improved mechanical properties of the HS sample were due to the persistent occurrence of the TWIP effect under very low to high strain levels during the entire deformation process, the effective grain boundary hardening in the EG domain, and the additional work hardening provided by the GNDs.

To address the issues of existing powder metallurgy particle reinforced composites, such as poor wettability between ceramic reinforcement and Al matrix, the toxicity of quasicrystal, the compositional limitations of high entropy alloy, and poor thermal stability of amorphous alloy reinforcement, etc. Al matrix composites reinforced with Co-based hard particles (M7) were synthesized by a powder metallurgy process. The effects of sintering temperature, M7 hard particle content, and particle size on the microstructure and mechanical behavior of the composites were investigated. The results show that as the sintering temperature rises, the interdiffusion reaction between M7 particles and Al matrix is enhanced, the diffusion layer becomes thicker, the in-situ generated intermetallic compounds such as Al3Ni2, Al13Cr2, Co2Al9 and Al72.5Co16.5Ni11 become more abundant, and parts of M7 particles gradually dissolve in the Al matrix and the interdiffusion layer disappeared. When the sintering temperature was raised from 580 degrees C to 640 degrees C, the microhardness and yield strength were improved from 23.9 to 34.7 HV0.1 and 40.9-175.2 MPa, respectively. The composites' mi-crohardness and strength increase as the M7 particle content increases. Meanwhile, the smaller the particle size, the greater the microhardness and yield strength. The strengthening mechanism of M7/Al composites is mainly attributed to the synergistic effects of the in-situ generated multiphase intermetallic compounds strengthening, solid solution strengthening, and M7 hard particles dispersion strengthening. Furthermore, the M7/Al composites' microhardness and strength were respectively 27.6% and 146.1% higher than those of the SiC/Al composites containing the same size and content of SiC particles, which is mainly due to the good interfacial wettability between M7 and Al matrix. It indicates that metal-based hard particles could be better alternative reinforcements to produce high performance composites.(c) 2023 Elsevier B.V. All rights reserved.

Metal-matrix composites with high damping capacity and excellent energy absorption properties have extensive application requirements. Porous TiNi shape memory alloys with a three-dimensional connected structure were firstly prepared by powder metallurgy technology consisting of "uniform-mixing, compaction, dissolution and sintering" four stages. Then, the novel Acrylic/TiNi composites were manufactured in light of vacuum negative pressure infiltration technology. The damping properties were characterized by internal friction. It was found that Acrylic/TiNi composites exhibit a much higher damping capacity than that of corresponding TiNi porous materials, especially in around room temperature zone. It was rationalized that the great improvement of the damping capacity is originated from the intrinsic high-damping of Acrylic phase as well as induced massive interface damping between TiNi porous matrix and Acrylic phases. The quasi-static compressive mechanical measurement shows that Acrylic/TiNi composites can achieve energy absorption efficiency similar to that of TiNi porous alloy, the reason of which is confirmed to be associated with the longer and smoother compression plateau area of TiNi composites. In addition, the full penetration of the Acrylic reinforced phase greatly enhances the energy absorption capacity and yield strength of the composites. Deformation mechanism analysis of the TiNi composites indicates that the mutual compensation and coupling between porous matrix and Acrylic fillings during the compressive process can be considered to account for the improved energy absorption characteristics.

Porous Cu–Al–Ni shape memory alloys (SMAs) are fabricated via powder metallurgy method using Cu, Al, Ni powders and Cu–Al–Ni alloy powder as raw materials, respectively. It is found that the two kinds of specimens have similar macroscopic morphologies: connected pores are uniformly distributed in the Cu–Al–Ni matrix, forming a 3D network structure. By comparison, the specimen fabricated using alloy powder has much finer microstructures than the specimens fabricated using Cu, Al, Ni powders. After adding Ce element to the latter, the microstructure of the Cu–Al–Ni matrix is significantly refined because of the formation of Ce‐rich particles. Damping tests show that the latter has superior damping capacity than the former. With the increase of Ce content, the damping of the latter increases first and then decreases. When the Ce content reaches 0.05 wt%, the highest damping can be achieved. Correlated mechanisms are discussed based on the microstructural observations.