Modified 9Cr–1Mo (P91) steel components that are used in thermal power plants undergo creep degradation during long-term service at 600 °C. This study examines the effect of a short-term rejuvenation treatment (RT), involving normalizing at 1050 °C for 2 h followed by tempering at 750 °C for 2 h, on the creep life enhancement of partially crept P91 steel at 600 °C and 135 MPa. The creep response of rejuvenated P91 steel is compared with its as-received counterpart, which is creep-tested until rupture. Results reveal that the short-term RT erases the creep history in partially crept P91 steel and enhances creep life by approximately 4 times compared to its as-received counterpart. Microstructural analysis reveals that creep leads to lath coarsening, deviates the orientation relationship (OR) between laths and prior austenite grain (PAG) from the ideal Kurdjumov–Sachs (K–S) OR, Oswald ripening of M23C6 precipitates, and a reduction in dislocation density, ρ. RT on the partially crept P91 leads to a complete microstructure reversal, wherein the microstructural features match well with the uncrept as-received sample subjected to the same treatment. Microstructural evolution during creep, involving the competition between dislocation climb-assisted lath coarsening and lath boundary pinning by M23C6 precipitate, is discussed and numerically estimated from the continuum damage model (CDM). Correlations are established between the initial lath width, lath coarsening kinetics, steady-state lath width, and creep rate. Implications of these results on extending the life of P91 components and the effectiveness of RT compared to similar rejuvenation treatments on other high-temperature alloys are discussed.

Reliable joining of Al stranded wires to Al connecting tubes is essential for Al-core power cables. Magnetic pulse welding (MPW) provides a solid-state route for joining similar Al materials, but the stranded-wire/tube configuration introduces spatially nonuniform collision conditions, leading to pronounced regional differences in interfacial morphology, microstructure, and performance. In this study, Al tube/Al stranded-wire MPW joints fabricated at discharge voltages of 12-18 kV were investigated to elucidate the resulting interfacial evolution and performance response. With increasing voltage, the interface evolves from unbonded or discontinuously bonded states to continuous bonding accompanied by interfacial waviness, with Region II developing a continuous wavy interface earlier than Region I. EBSD and TEM reveal the formation of an interfacial grain-refinement band, upgrading of the grain-boundary network, and a defect gradient from dislocation tangles near the weld center to dislocation walls/cellular structures toward the base material. Nanoindentation shows a progressively broadened and intensified interfacial hardening peak, especially in Region II. Macroscopically, contact resistance decreases rapidly and stabilizes as voltage increases. Tensile failure shifts from interfacial pull-off at 14 kV to fracture of the Al strands at >= 16 kV. These results identify 16-18 kV as the optimal processing window under the present conditions and provide a basis for quality assessment of Al stranded-wire/tube MPW joints.

Metal-film-based conductors are an important element of flexible electronic devices. However, they typically suffer from fatigue damage and electrical degradation under cyclic deformation, which can limit practical use. Here we report fatigue-resistant metal films with a coherent gradient nanolayered architecture. The architecture consists of alternating stacked layers of silver and aluminium, with silver layers that become progressively thinner and finer grained. Initial crack nucleation is delayed by a combination of heterodeformation-induced strengthening, controlled grain coarsening in the silver layer and mitigation of interface stress concentrations. The moderate interface adhesion between silver and aluminium, and the multiaxial stress state induced by the gradient structure, also promote interface delamination and crack deflection, which suppresses fatigue-crack propagation. Our coherent gradient nanolayered silver/aluminium films exhibit a conductivity of over 107 S m−1 and relatively little conductivity change in both high-cycle, low-stress regimes (107 cycles at 0.7

Site-specific grain-structure control is desirable for turbine blades with region-specific performance requirements. Here, we demonstrate that a columnar-to-equiaxed transition can be initiated in electron-beam additive manufacturing within individual melt pools and retained through controlled overlap ratio and melt pool geometry. A high overlap ratio with shallow melt pools increases grain density and suppresses competitive dendritic growth, yielding near-equiaxed grains with an average size of ∼30 μm on single-crystalline substrates. A tailored heat-treatment protocol incorporating optimized recovery annealing relieves stresses while preventing recrystallization, thereby stabilizing the refined microstructure. This strategy enables grain structure design without altering established alloy compositions.

The microstructural features of additively manufactured alloys are distinct from those of their conventionally manufactured counterparts, with the combination of the alloy and the processing methods and parameters imparting uniqueness. Herein, we report one such distinct, and hitherto unreported, feature of mesoscale concentric tree-ring-like microstructure within the columnar grains in the Ni-based superalloy fabricated using the laser directed energy deposition technique. Each columnar grain comprises dendrites tens of micrometers in width. Within individual dendrite, cylindrical concentric patterns develop with radial axes perpendicular to the build direction, characterized by relatively coarsened gamma(y) precipitates along concentric walls and finer precipitates between them, producing a tree-ring-like morphology on the laser scan plane. Elemental segregation and dislocation distributions correlate with both the dendritic framework and concentric patterns. Their formation is attributed to the coupled effects of microsegregation-induced intradendritic solvus temperature gradients and thermomechanical cycling that occurs during layerwise fabrication.

Liquid-metal (LM)-based stretchable conductors are promising for soft electronics, yet their practical use is limited by high material costs and susceptibility to leakage. Here, we report a multilayer architecture comprising a top Cu layer, a Cu-SEBS hybrid layer, a Cu-GaCu2-SEBS-LM composite layer, and a micron-scale SEBS layer, which decouples mechanical strain from electrical conduction. This design couples strain-induced microcracked Cu films with strain-isolated out-of-plane and in-plane conductive pathways, eliminating strain-dependent resistance variations. Remarkably, the conductor achieves strain-invariant high conductivity (on the order of 107 S m-1) over 0-920% strain with an ultralow LM loading of only 5 vol %. Critically, it exhibits exceptional leakage resistance across the entire stretching range, addressing a longstanding challenge in LM-based electronics. As a proof of concept, we demonstrate its applicability as stretchable electrodes for real-time physiological signal monitoring and machine-learning-assisted gesture recognition, highlighting its potential for next-generation wearable bioelectronics.

Magnetic-pulse-welded Al tube/Al stranded-wire joints undergo repeated heating and cooling during long-term current-carrying service, where interfacial stability directly governs service reliability. In this study, current-induced thermal cycling tests combined with SEM, EBSD, TEM, contact resistance and tensile measurements were performed to investigate the interfacial and microstructural evolution. Local debonding initiated and gradually propagated along the flat interface in Region I, whereas the wavy interface in Region II retained continuous bonding after 1000 thermal cycles. Near-interface deformation structures underwent dislocation rearrangement and recovery, forming dislocation walls and recovered substructures. With increasing cycle number, the contact resistance increased and the tensile performance decreased, while all specimens fractured on the Al stranded-wire side. These results demonstrate that the wavy interface exhibits superior thermal-cycling stability by suppressing debonding propagation and maintaining stable bonding.

Direct photolithography of colloidal quantum dots (QDs) via photoinitiated thiol-ene click chemistry has emerged as an attractive approach for the fabrication of high-resolution QD-based displays, benefiting from its site-controlled and byproduct-free reaction pathway. Nevertheless, this approach remains constrained by limited colloidal stability and suboptimal optoelectronic performance, stemming from spontaneous ligand exchange and unfavorable reaction kinetics. To address these challenges, we introduce a dual-ligand passivation strategy that replacing native QD ligands with rationally designed alkenyl ligands with strong binding affinity and high reactivity. This strategy confers a ~ 6-fold enhancement in the storage lifetime and a ~ 15-fold improvement in photolithographic efficiency. These advances enable the direct photopatterning of QDs with an ultrahigh resolution exceeding 18,000 PPI (pixel size: ~ 0.77 u03BCm), at an ultralow-energy dose of ~ 1 mJ/cm2. Furthermore, the fabricated light-emitting diode with the crosslinked dual-ligand passivated QD (DLP-QD) and nano-patterned DLP-QD achieved peak external quantum efficiencies of 21.17% and 15.67%, respectively, ranking among the state-of-the-art devices in this field. This work demonstrates the promise of robust and efficient thiol-ene click chemistry enabled by dual-ligand passivation for direct QD photolithography, paving the way for high-performance QD-based displays and advanced optoelectronic devices toward industrial applications.

To clarify the long-term service stability of magnetic pulse welded (MPW) Al tube/Cu stranded-wire cable joints, joints fabricated at 16 kV were subjected to temperature-rise thermal cycling for 250, 500, and 1000 cycles. The evolution of the Al/Cu interfacial microstructure, phase constitution, contact resistance, and tensile behavior was systematically investigated by combining SEM-EDS, TEM-SAED, HRTEM, and electrical and mechanical testing. The results reveal that thermal-cycling-induced interfacial degradation is markedly region-dependent. Region I develops a continuous Al2Cu/AlCu/Al2Cu3/Al4Cu9 multilayer IMC structure along the interface-normal direction, with localized IMC/Cu delamination after 1000 cycles. Region II exhibits localized IMC thickening at wave troughs, forming an Al2Cu/AlCu bilayer that subsequently develops through-thickness cracking. Region III evolves predominantly into Cu-rich Al2Cu3 and Al4Cu9 phases, accompanied by crack propagation and brittle spalling. The contact resistance increases from approximately 27 μΩ to 37 μΩ after 1000 cycles (~37% increase), and the peak tensile load and fracture displacement decrease synchronously; nevertheless, failure remains dominated by fracture of the Al outer tube rather than global interfacial pull-off. Mechanistically, the degradation is governed by the synergistic effects of IMC thickening and Cu enrichment, interfacial cracking and delamination, reduction of the effective metallic conduction area, and recovery softening of the Al outer tube. These findings demonstrate that the initial IMC thickness and interfacial geometry collectively control the region-dependent degradation pathways and provide a mechanistic basis for service reliability assessment of MPW Al/Cu cable joints.

A collision-synchronous auxiliary pulsed-current-assisted magnetic pulse welding process was proposed by connecting a 3 mF/2 kV auxiliary capacitor bank across the tube-to-rod ends, enabling pulsed-current injection through the newly established transient interfacial conduction path after initial collision. Using AA6063-T6 tube/rod joints, interfacial microstructural evolution and mechanical response were investigated under auxiliary currents of 0, 35 and 70 kA. EBSD results show that the auxiliary current broadens the local interfacial refined zone from ∼10 μm to ∼50 μm, with selective petal-like extension from wave troughs into the base metal. TEM observations reveal progressive dislocation rearrangement from dislocation tangles to dislocation walls and sub-boundaries, supporting recovery and CDRX-related microstructural evolution. Nanoindentation identifies a widened hardness plateau of ∼55 μm at 70 kA. Although tensile failure remains base-metal-controlled, the auxiliary pulsed current markedly extends the effective local strengthened layer near the interface.

To optimize the mechanical strength and ductility of low-oxygen Titanium-Zirconium-Molybdenum (LO-TZM) alloys, systematic solution-quenching heat treatment was applied to specimens with various oxygen concentrations. Remarkable microstructural evolution was observed in the alloy with an oxygen content of 280 ppm: nanoscale Ti-rich precipitates (∼20 nm in diameter) formed within the molybdenum (Mo) matrix. The refined microstructure yields an ultimate tensile strength of 733 MPa and exceptional ductility (28.7 % elongation). The stress–strain curve exhibited a distinct yield plateau accompanied by macroscopic Lüders band formation, evidencing substitutional solid solution strengthening. The enhanced plasticity is attributed to three synergistic mechanisms: (1) elimination of embrittling coarse oxide inclusions via oxygen reduction, (2) precipitation strengthening from solution-derived nanoscale Ti-rich phases, and (3) improved grain boundary cohesion due to suppressed oxygen segregation. These combined effects enable the alloy to retain high strength meanwhile achieving unprecedented ductility. Importantly, the nanoscale Ti-rich precipitates exhibit superior thermal stability, retaining their morphological integrity even after exposure to high-temperature environments. This characteristic further expands the alloy’s potential for high-temperature service scenarios.

In this study, a continuous coating with a thickness of 20 μm and intimate bonding to the substrate was in situ fabricated on the TZM alloy (Mo-0.6Ti-0.08Zr-0.04C) via high-temperature gas-phase carburization at 1200 °C combined with water quenching, using CO as the carbon transport carrier. The coating possesses a fine equiaxed grain structure with an average grain size of 1.48 μm, and its microhardness reaches 1479 ± 42 HV. This modification process does not sacrifice the inherent strength and ductility of the TZM alloy matrix, while it does reduce the wear volume of the alloy by 78.8% in comparison with the uncoated rolled TZM alloy.

The effects of pre-deformation, conventional aging and pulsed current aging on the mechanical properties and microstructure of 7150 aluminum alloy were comparatively investigated. The research results indicate that only the synergistic effect of pre-deformation and pulsed current aging was most beneficial for improving the strength of 7150 aluminum alloy, which was mainly attributed to the coupling effect of pre-deformation and pulsed current promoting the transformation of GP region into η′ phase. Pre-deformation introduced dislocations to provide nucleation sites for the η′ phase, and the non-thermal effect of pulsed current promoted atomic diffusion and reduced the nucleation energy barrier of the η′ phase, resulting in the main precipitation phase in the 6% + EAA sample being the η′ phase. In addition, there was little difference in dislocation density and grain size between the 6% + CA sample and the 6% + EAA sample, and their strength increase was mainly due to precipitation strengthening.

Ni-based superalloys are critical materials in aerospace and power generation industries due to their exceptional high-temperature performance, achieved through carefully designed chemical compositions and meticulously controlled microstructures. Traditionally, these components are manufactured through subtractive processes that are costly and time-intensive, yet even these high-value components are prone to damage during prolonged service in harsh environments, necessitating innovative methods for manufacturing, remanufacturing, and repair. Recent advancements in 3D-printing technologies have demonstrated significant potential in addressing these needs, particularly for nonweldable Ni-based superalloys, but formidable challenges remain. Key issues include preventing crack formation, controlling crystal grain structure, and optimizing precipitate volume fraction and morphology to enhance mechanical properties. Here, an overview of the recent studies that have elucidated fundamental mechanisms underlying these challenges, such as elemental microsegregation, melt pool morphology, and the spatiotemporal distributions of microscopic defects and stresses, is presented. Based on these insights, strategies involving the optimization of printing parameters and the implementation of heat treatments are developed to improve the printability and microstructural controllability. By examining the fabrication of a turbine blade as an example, this review highlights the progress made, the persistent challenges, and future opportunities for the 3D printing of high-performance Ni-based superalloy components.

The effect of solution temperature and cooling rate on the microstructure and coarsening behavior of gamma' precipitates, as well as the hardness of DZ125 Ni-based superalloy is investigated. Microstructural analysis reveals distinct differences in gamma' precipitate morphology between the dendrite cores (DCs) and interdendritic regions (IRs). At lower solution temperatures (1220 degrees C), gamma'-particles do not completely dissolve, leading to the co-existence of primary gamma' (similar to 540 nm) and smaller spherical secondary gamma' (similar to 50 nm) precipitates in IRs, while higher temperatures (1240-1260 degrees C) leads to coarser and more cuboidal secondary gamma' particles. Water quenching, produces finer gamma' particles (similar to 158 nm) near the surface whereas slower cooling methods like furnace cooling results in larger particles due to extended diffusion times. Both the gamma' area fraction, A(gamma'), and the hardness increases with increasing solution temperature and depth. While furnace cooled DZ125 exhibits the highest hardness of similar to 470-480 HV, water-quenched samples have the lowest hardness of similar to 430-440 HV and exhibit a gradient in the hardness along the cross-section. A clear correlation between A(gamma') and Vickers hardness is observed and the solution treatment at 1240 degrees C followed by furnace cooling leads to the highest enhancement in hardness. gamma' coarsening mechanisms are discussed by considering the fits of Lifshitz-Slyozov-Wagner (LSW) model, also known as matrix-diffusion controlled model, and trans-interface diffusion-controlled (TIDC) model. Goodness-of-fit measures reveal that the coarsening kinetics undergoes a transition from LSW near the surface to TIDC in the bulk. These results help in developing heat treatment strategies for directionally solidified Ni-based superalloys.

Induction heating favors crack inhibition for laser additive manufacturing of Ni-based superalloys but may negatively influence columnar grain growth and mechanical properties. Here, by induction heating at a proper temperature during laser additive manufacturing, superalloys with a directionally solidified grain structure are obtained. Optimized gamma '-precipitate size grants them higher microhardness than their counterparts either cast or additively manufactured without concurrent induction heating. Furthermore, lowered built-in dislocation density reduces the driving force for recrystallization. The combination of a maintained columnar grain structure, an increased microhardness, and a decreased risk of recrystallization offers a valuable pathway for advancing additive manufacturing of superalloys.

Amorphous–crystalline dual-phase grain structure often enables materials with unique performance. This is especially the case for the garnet-type solid-state electrolyte Li 7 La 3 Zr 2 O 12 (LLZO), which is a promising candidate for hybrid and all-solid-state lithium batteries. A major synthesis challenge, however, is that amorphous LLZO is difficult to retain via conventional sintering and even Flash Joule heating. Using electron beam focused to sub-millimeter scale with point-by-point scanning, we achieved highly localized heating to very high temperature followed by ultrafast quenching, enabling the direct fabrication of uniformly fine-grained amorphous–crystalline dual-phase LLZO. Fast ion transport offered by the crystalline grains, together with the amorphous shell that promotes a more homogeneous space-charge distribution at grain boundaries, markedly enhance the critical current density, cycling stability, and optical transparency. Our scalable fabrication route offers unparalleled tunability in electrochemical performance, and also has broad applicability for other functional ceramic systems requiring optimized electrical and optical properties.