Journal of Materials Science最新文献

This study decodes the multiscale interaction between texture and dislocations during microplastic deformation using synchronous AE-TEM. Two samples with identical rolling reduction (70%) and annealing temperature (550 °C, 1 h) were examined: room-temperature rolled (RR) and cryo-rolled at − 70 °C (LR). Results show that a high proportion of low-angle grain boundaries (LAGBs) increase mobile dislocation density during microplastic deformation, but an excessive proportion in LR hinder dislocation motion, reducing activity. Three textures—{112} < 110 > , {100} < 110 > , and {111} < 110 > —were identified in both samples, with {100} < 110 > dominant in RR and {111} < 110 > primary in LR. The LR texture facilitates dislocation slip more than RR. Combining LAGBs and texture effects, this study suggests a synergistic regulatory role on microplastic deformation, influencing dislocation generation, multiplication, and cooperative motion. AE-TEM analysis reveals that dislocation multiplication dominates in both RR and LR, with higher activity in RR. Multiplication precedes cooperative motion, exhibiting a competitive tendency, especially in RR. The higher slip resistance texture and lower dislocation density in RR promote earlier multiplication and delayed cooperative motion compared to LR. Due to synergistic regulation, RR formed a high-density dislocation region. Proliferation signal amplitude and energy increased by 16% and 86%, respectively, while cooperative motion signals decreased by 16% and 3 times. Based on distinct deformation mechanisms, this paper proposes a characterization method integrating AE technology with microplastic damage assessment, advancing understanding of plastic deformation in metallic materials.

Titanium alloys are promising materials for marine engineering equipment and infrastructures due to their low density, high strength and excellent corrosion resistance. However, stress corrosion has been regarded as one of the most significant threats for titanium alloys, which may lead to cracking and serious failure. Welding is the most important method for the fabrication and combination of large titanium alloy structures and components, and the stress corrosion susceptibility of the welded joint differs substantially from the base metals. This work investigated the stress corrosion behaviors of the gas tungsten arc welded (GTAW) joint of TC4 titanium alloy by comparing the electrochemical and microstructural characteristics and also the crack propagation behaviors of base metal (BM), heat-affected zone (HAZ) and weld metal (WM). The K_ISCC value followed the order WM > HAZ > BM. The corrosion resistance assessed via electrochemical impedance spectroscopy (EIS) was the highest at WM and lowest at BM, correlated well with the quality of the passive film assessed by Mott–Schottky measurements. The microstructure has been found to influence the crack propagation in the view of microstructural uniformity and texture strength. The typical equiaxed structure of BM favored the crack propagation, while the typical lamellar structure and the acicular martensite phases in WM inhibited crack propagation and caused deflection of the crack path.

Pipelines are the most economical and efficient means for large-scale, long-distance transport of hydrogen gas, helping accelerate the realization of a hydrogen economy. Today, the development of hydrogen pipeline projects, including repurposing existing pipelines for hydrogen service, has become a global focus, especially in major energy producing and consuming countries. However, steel pipelines are prone to hydrogen embrittlement (HE) in high-pressure gaseous hydrogen environments, which can lead to pipeline failure. Drawing on published work, we assemble a curated knowledge base that distills how gaseous hydrogen embrittlement in pipelines is understood, characterized, and evaluated.

The controlled synthesis of zinc oxide ceramics with tailored morphology and crystallinity remains central in advancing its functional applications. The use of protein-based eggshell membrane as a template for synthesizing zinc oxide resulted in the formation of single-crystal platelets and polyhedrons. The eggshell membrane as a template is capable of providing active sites for ion coordination and nucleation. Structural and morphological analysis confirmed the evolution of an assembly of nanocrystallites anchored on a fibrous network replicating the interwoven structure of eggshell membrane into single-crystal platelets and polyhedrons at relatively higher calcination temperatures. Transmission electron microscopy investigations revealed the coalescence of primary nanocrystallites into larger single-crystal domains and the presence of coherent lattice junctions across the attachment interfaces, indicating oriented attachment growth, a non-classical crystal growth process, as a plausible mechanism for the growth of ZnO single crystals. The protein-rich eggshell membrane contains functional groups that can interact with inorganic precursors, providing nanoscale confinement that promotes aggregated growth of crystallites favourable for oriented attachment. The results of this study offer insights into crystal engineering through bio-templating and also demonstrate the utility of eggshell membrane as a platform for the green and sustainable synthesis of metal oxides.

Graphical abstract

TA36 is a novel low-cost near-α titanium alloy independently developed in China, but it is prone to cracking during cold working. This study revealed the deformation behavior and crack nucleation mechanism during the cold deformation process of TA36 lamellar structure through in-situ tensile tests combined with in-situ EBSD technology. The research found that after cold deformation of the TA36 lamellar structure, numerous GNDs were formed at the grain boundaries and within the grains where no slip lines appeared, and GNDs further hindered the slip process. Due to the anisotropy of the coarse lamellar structure, it is not conducive to the initiation of the base plane and prismatic slip systems. The activated slip systems are mainly pyramidal slip systems (01 (stackrel{text{-}}{1}) 1)[(stackrel{text{-}}{2}) 110], (10 (stackrel{text{-}}{1}) 1)[1 (stackrel{text{-}}{2}) 10] and ((stackrel{text{-}}{1}) 10 (stackrel{text{-}}{1}))[11 (stackrel{text{-}}{2}) 0], with only a small number of prismatic slip systems (01 (stackrel{text{-}}{1}) 0)[1 (stackrel{text{-}}{2}) 10] activated. Cracks originated at the intersection of trigeminal grain boundaries and the slip zones where stress concentration was relatively severe, and then quasi-cleavage fractures occurred.

Magnetic Tunnel Junctions (MTJs) operate on the principle of spin-dependent tunneling through an ultrathin insulating barrier, and their magnetoresistive response depends on the relative alignment of magnetization within the two ferromagnetic layers. In this work, the free-layer thickness controls the magnetization states and magnetotransport behavior of CoFeNi/MgO/CoFeNi MTJs by means of micromagnetic simulations. The findings show a clear transition in thickness from coherent single-domain rotation towards vortex-mediated reversal. This transition, in turn, directly controls the Tunneling Magnetoresistance (TMR) observed to change in polarity from +199% at 25 nm to −344% at 100 nm. The coercive field moderately increases from 22.3 mT to 24.9 mT as a function of thickness, which attests to the transition between uniform and non-collinear magnetization configurations. Thus, the polarity inversion in sign arises from the formation of vortex states at larger thicknesses, which create non-collinear interfacial spin alignments and enhanced spin-flip tunneling, resulting in the reversal of the effective spin polarization. The research provides systematic insights into the thickness-dependent magnetic configurations, energy landscapes, and transport behavior in CoFeNi-based MTJs, with conclusions important for further prospective memory and logic devices.

In the realm of titanium alloys, achieving a balance between strength and ductility in high-oxygen Grade 4 commercially pure titanium (CP-Ti) remains a critical challenge, primarily due to oxygen-induced embrittlement and limited deformation mechanisms. This study examines the microstructural evolution of Grade 4 CP-Ti subjected to cold rolling. Multi-pass rolling is shown to induce progressive grain refinement, with the microstructure transforming from an initially equiaxed morphology to a highly elongated fibrous structure. A key observation is the apparent geometric dilution of oxygen and iron segregation at grain boundaries (GBs). Analysis indicates that this effect is predominantly governed by the drastic increase in specific grain boundary area, rather than by chemical desegregation. Dislocation slip, primarily accommodated by prismatic < a > and pyramidal < c + a > systems, gives rise to a distinct interaction with the evolving grain boundary network. Although the geometric dilution of embrittling solutes alleviates premature intergranular fracture, the depletion of work-hardening capacity associated with the high dislocation density ultimately constrains ductility. Overall, this work clarifies the competing mechanisms underlying the strength–ductility in high-oxygen CP-Ti and offers theoretical insight for future studies on high-oxygen pure titanium and its alloys.

Graphical abstract

This work figures out the effect of capping concentration on structural, morphological, optical, and electrochemical properties of Cu₂ZnSnS₄ (CZTS) quantum dots and inspects its potential as p-type absorber layer for photovoltaic applications. While numerous wet chemical routes for synthesizing CZTS have been reported, the present work focuses on elucidating the critical role of PVP in this process, an aspect that remains insufficiently explored. Three different samples of CZTS quantum dots were synthesized through a facile solvothermal synthesis route, with varying PVP concentrations of 2 g, 1 g, and 0 g, respectively. Detailed analysis of the as-synthesized sample revealed the formation of quantum dots owing to kesterite crystal structure. The information regarding structure, morphology, and composition was inferred from XRD, micro-Raman, FESEM with EDAX, DLS, and HRTEM analysis. The optical properties were evaluated through UV–Vis diffuse reflectance spectrum. Electrochemical techniques, such as cyclic voltammetry and impedance spectroscopy, were utilized to probe the electron transfer properties and band gap of the samples. Thorough analysis from characterization results indicated that the concentration of 1 g of PVP can enhance the optical, structural, and electrochemical properties of CZTS nanomaterials. It yielded quantum dots with least agglomeration, and crystallite size falls around 4.6 nm. In addition, stoichiometry is apt for 1 g concentration of PVP. Also, the band gap values obtained from Kubelka–Munk plot are in well accordance with the cyclic voltammetry results and fall in the required range suited for efficient absorption in solar cell. This material was incorporated to form a heterojunction structure of glass/SnO₂/F/TiO₂/Cu₂ZnSnS₄/Ag to analyze its device performance.