In dual-phase Mg-Li alloys, constructing a heterogeneous microstructure-consisting of coarse original alpha-Mg and fine secondary alpha-Mg precipitates-provides a promising approach to overcome the strength-ductility trade-off. This work systematically investigates the orientation evolution and variant selection of alpha-Mg in a dual-phase Mg-9Li-3Al-1(La/Ce) alloy during isothermal compression at 623 K under varying strain rates. The results demonstrate that original alpha undergoes continuous grain rotation under high strain rate, leading to an intragranular orientation gradients. Conversely, the high strain rate prioritizes the rapid release of deformation stored energy, resulting a high fraction of non-Burgers orientation relationship (non-BOR) interfaces and weak variant selection for secondary alpha precipitates. Notably, under low strain rates, a novel a-axis matching rule (< 111 >(beta 1)//< 111 >(beta 2)) is proposed for secondary alpha precipitates formed at grain boundaries (alpha '(GB)). This rule acts as a crucial adaptive crystallographic strategy to maintain optimal phase boundary matching when the classical c-axis matching rule ({110}(beta 1)//{110}(beta 2)) is geometrically restricted, thereby strengthening variant selection. Additionally, the low strain rates also induce the formation of secondary alpha precipitates within the matrix (alpha '(M)). Their weak variant selection causes a large number of alpha '(M) variants toward crystallographic orientations with high non-basal slip potential. This study provides crucial insights to design the high-performance heterogeneous dual-phase Mg-Li alloys.

Friction stir processing is an effective solid-state route for tailoring the microstructure and mechanical performance of dual-phase Mg-Li alloys, yet the evolution of phase coordination and interface behavior under different processing conditions remains insufficiently understood. In this work, a Mg-7.8Li-0.7Zn-0.4Sr-0.4Ca alloy was friction stir processed at different rotation speeds to establish the process-microstructure-property relationship. The grain size in the stir zone exhibited a non-monotonic dependence on rotation speed, and the optimum ultrafine-grained structure was obtained at 800 rpm, where the average grain sizes of alpha-Mg and beta-Li were refined to 3.01 and 3.71 & micro;m, respectively. The optimized sample achieved an ultimate tensile strength of 210 MPa and an elongation of 17.4%. The refined structure was stabilized by nanoscale MgZn2precipitates, whose thermal stability was enhanced by Ca and Sr co-segregation, thereby exerting an effective Zener pinning effect during friction stir processing (FSP). In addition, a rare deformation-induced FCC-beta-Li phase was identified in the stir zone, indicating a BCC -> FCC transformation under severe thermomechanical conditions. TKD analysis further showed that ultrafine alpha grains preferentially nucleated at triple junctions and alpha/beta interfaces following the Burgers orientation relationship with the beta matrix, and that selected variants formed at these sites. These mechanisms are expected to reduce interfacial energy and facilitate strain accommodation between the HCP alpha-phase and the BCC/FCC beta-phase. Together with texture modification, they contributed to the highest strength among the FSPed samples while maintaining a relatively high tensile elongation. This study provides insight into the microstructural regulation and strengthening mechanisms of dual-phase Mg-Li alloys processed by FSP.

This study overcomes the pervasive strength-damping trade-off in magnesium alloys via extrusion temperature control and aging of an Mg-8.9Gd-3.9Y-1.3Zn-0.8Mn alloy. ET450 produced a bimodal structure (3.2 & micro;m DRX grains) with 390 MPa UTS, outperforming the fully DRXed ET480 (5.1 & micro;m, 376 MPa). After peak aging of ET450 (ETA450), beta'/gamma ' nanoprecipitates strengthen the alloy to 510 MPa (+30.8% UTS) through dislocation shearing. Crucially, ETA450 retained a high damping capacity (Q- 1 = 0.018), rivaling the un-aged ET480 (0.021). This strategy of low-temperature extrusion and aging provides a new design pathway for high-performance Mg-RE alloys.

A high-performance Mg-8Li-3Zn-2.5Er alloy sheet with layered structures was fabricated via extrusion and online heating rolling. After online heating rolling, the alloy exhibited a tensile strength of 288 MPa, a yield strength of 245 MPa, an elongation of 13.3%, and the specific strength of 182 kN & sdot;m kg-1, indicating an excellent strengthductility synergy. Microstructural analysis revealed that dynamic recrystallization (DRX) occurred in the extruded alloy, resulting in significant grain refinement. In addition, a large number of dislocations and dispersed precipitates were observed in the alpha-Mg matrix. After rolling, fine MgLiZn phases precipitated at the grain boundaries of beta-Li phases, inhibiting grain growth, and refined the grain size. Moreover, rolling activates abundant dislocations within the alpha-Mg phase, contributing to pronounced work hardening. A high density of stacking faults (SFs) was also generated in the rolled alloy. Nano-sized precipitates dynamically formed along the SFs and exhibited coherent interfaces with the alpha-Mg matrix, providing strong resistance to SF migration. In addition, dislocation accumulation around the SFs was observed, and the synergistic interaction between dense SFs and fine nano-precipitates effectively impeded dislocation motion, resulting in further strengthening of the alloy. These results demonstrate that the combined regulation of grain structure, dislocations, stacking faults, and precipitates through tailored thermomechanical processing offers an effective strategy for developing highstrength and high-toughness Mg-Li alloys.

The core outlet temperature is an important safety parameter for pressurized water reactors (PWRs), and its accurate determination depends on highly reliable thermocouple sensors. In this study, two typical commercial K-type thermocouple alloys (de1 and de2) were used to fabricate mineral-insulated metal-sheathed (MIMS) thermocouples. A comparative severe accelerated aging test at 500 °C for 168 h was performed to investigate electromotive force (EMF) stability under high-temperature exposure conditions. After aging, both alloy types exhibited obvious positive EMF drift, and the maximum drift magnitude appeared at the calibration temperature of 400 °C. The measured irreversible EMF drift of de2 thermocouples was lower than that of de1 thermocouples. For the same de2 alloy, thermocouples fabricated with pre-oxidized thermoelement wires presented smaller irreversible drift than those made of bright wires. Reversible EMF drift and heating–cooling calibration hysteresis were more significant for de1 specimens. Stabilization treatment at 570 °C for 2 h followed by furnace cooling effectively reduced the thermal hysteresis of both alloys during temperature cycling. This study provides straightforward experimental data and practical processing references for optimizing the manufacturing route of nuclear-grade MIMS thermocouples with improved high-temperature EMF stability.

Dual-phase LZ91 Mg-Li alloys possess an ultralow density with moderate strength. Clarifying the relationship among load transfer, deformation mismatch and interfacial damage in the soft beta-Li/hard alpha-Mg heterostructure is essential for improving their performance. This study used in-situ synchrotron diffraction to monitor the stress evolution, lattice strains and defect accumulation in both phases. The results reveal a three-stage process characterized by early yielding of beta-Li, alpha-Mg-dominated load bearing in Stage II, and reverse load redistribution to beta-Li at high strain. The diffraction data further show pronounced orientation-dependent lattice-strain evolution and peak broadening in both phases. The KAM map at similar to 2% strain indicates enhanced local misorientation near alpha/beta interfaces, while HR-DIC at 5% directly reveals severe interfacial strain localization and microcrack initiation. These findings provide insight into the stage-dependent load redistribution, interphase mismatch evolution, and interface-controlled damage in dual-phase LZ91.

This study investigates the influence of cold-working deformation on the electromotive force (EMF) calibration characteristics, hysteresis behavior, and long-term stability of the Type-K mineral-insulated metal-sheathed (MIMS) thermocouples used in Combination Fixed In-Core Detector Assemblies for pressurized water reactor nuclear power plants. Reduction ratios of 12%, 28%, and 38% were investigated, and samples were subjected to heating-cooling calibration and in situ aging tests. The results show that increased cold-working deformation leads to greater negative EMF deviation and larger heating-cooling hysteresis, mainly affected by the degradation of the positive KP thermoelement. Cold-working lowers the atomic diffusion activation energy and accelerates element migration, resulting in pronounced EMF drift during isothermal aging at 350 °C for 720 h. After aging below the order-disorder transition temperature, stable ordered structures form in the thermoelement alloys and hysteresis is significantly reduced. However, within the range investigated in this study, deformation above 28% imparts irreversible effects. The EMFs of 28% and 38% deformed samples remained lower than that of the undeformed state even after isothermal aging at 700 °C for 500 h. These findings reveal that excessive cold-working deformation severely impairs the measurement accuracy and long-term stability of the thermocouples, highlighting the necessity of the strict control of drawing deformation to ensure the reliability of nuclear-grade thermocouples under both normal and abnormal reactor operating conditions.

Mg-Li alloys are the lightest structural metallic alloys, with their crystal structure evolving from hexagonal close-packed alpha-Mg to body-centered cubic beta-Li with increasing lithium content. The emergence of the beta-Li phase fundamentally alters deformation behavior, enabling additional slip systems and new pathways for microstructure and texture control. In this study, the microstructural evolution, texture development, and mechanical response of an alpha + beta dual-phase Mg-8Li-3Al-1Sn (LAT831) alloy and a single beta-phase Mg-11Li-3Al-1Sn (LAT1131) alloy processed by extrusion and subsequent rotary swaging were systematically investigated. Rotary swaging induces pronounced microstructural refinement in the dual-phase LAT831 alloy, whereas the single beta-Li LAT1131 alloy shows limited grain refinement but significant texture modification. In the LAT831 alloy, extrusion followed by rotary swaging produces a dominant <101 & strns;0>///ED texture with a weak {0001}perpendicular to ED component. Rotary swaging further introduces lamellar twins and ultrafine grains, weakens the initial extrusion texture in the alpha-Mg phase, and enhances the alpha-fiber (<110 >//ED) component in the beta-Li phase. In contrast, the beta-Li phase in the LAT1131 alloy retains stable alpha- and gamma-fiber textures after rotary swaging, accompanied by an overall increase in texture intensity and the development of strong {111}<110> and {112}<110> components. Meanwhile, a strain-induced phase transformation from the beta-Li phase to the alpha-Mg phase is observed in both rotary swaged alloys. Visco-plastic self-consistent simulation (VPSC) reveals that deformation in the LAT831 alloy is dominated by {110}<111> slip in the beta-Li phase together with basal and prismatic slip in the alpha-Mg phase, while the progressive activation of extension and contraction twins further accommodates c-axis strain. For the LAT1131 alloy, deformation is jointly governed by {110}<111> and {112}<111> slip in the beta-Li phase.

In the current era of continuous innovation in materials science,ultra-light Mg-Li alloys have become a cutting-edge research focus due to their unique advantages[1].Mg-Li al-loys with a density of 1.3-1.65 g/cm3,are about 1/3 of that of Al alloys.It has excellent specific strength,specific stiffness,formability,and seismic performance,making it an excellent material for structural components[2].Moreover,their excep-tional resistance to high-energy particle penetration,electro-magnetic shielding capability,and thermal conductivity endow them with substantial application potential in structural ma-terials such as the shells and frames of aerospace electronic products[3,4].

This study systematically investigated the effects and underlying mechanisms of Cryogenic Multidirectional Forging (CMDF) passes on the three-dimensional (3D) microstructure, mechanical properties, and anisotropy of a 7A09 ultra-high strength aluminum alloy. CMDF was conducted with 0, 3, 6, and 9 passes. The evolution of grain structure, recrystallization behavior, texture, and second-phase precipitation along the X, Y, and Z directions were analyzed using electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and tensile testing. The results indicate that with increasing forging passes, the accumulated strain and multidirectional deformation effectively promote dynamic recrystallization and grain refinement, and the most significant grain refinement was achieved after 6 passes, with average grain sizes in the three directions being 26.3 & micro;m, 19.4 & micro;m, and 22.2 & micro;m, respectively. Multidirectional deformation effectively promotes dynamic recrystallization and grain refinement. The optimal grain refinement (average grain size of 19.4-26.3 & micro;m) and the highest strength (average ultimate tensile strength of 580.7 MPa and yield strength of 523.4 MPa) were achieved after 6 passes. The best microstructural homogeneity and peak ductility (average elongation of 15.1%) were obtained after 9 passes. At the micro-scale, CMDF significantly refined the MgZn2 second-phase particles, promoted the precipitation of high-density nano-sized ti ' phases after aging, and resulted in wider precipitate-free zones (PFZs) along grain boundaries. Multidirectional loading effectively broke the initial texture, markedly reducing the differences in grain size, texture intensity, and recrystallization degree among the three dimensions. The anisotropy index of mechanical properties continuously decreased with increasing passes, reaching its minimum after 9 passes. Analysis of strengthening mechanisms revealed that the superior comprehensive properties originated from the synergistic effects of grain refinement strengthening, second-phase strengthening, dislocation strengthening, and grain boundary strengthening. This research elucidates the mechanism by which CMDF passes achieve microstructural homogenization and property enhancement via the regulation of 3D uniform deformation and the cryogenic suppression of dynamic recovery. This study provides a theoretical foundation for utilizing the CMDF process to reduce anisotropy and achieve a high strength-ductility combination in 7A09 aluminum alloy components.

The orientation relationship (OR) between precipitated needle-shaped alpha'-Mg and matrix (3-Li in a dual-phase Mg-Li alloy has been investigated. Most alpha'-Mg within the interior of (3-Li matrix (alpha M'-Mg) follow the Burgers OR: {0001} {110}, (1120) (111), while alpha'-Mg at phase boundaries (alpha PB'-Mg) deviate from the Burgers OR, forming specific angles with the original alpha-Mg in the common (1120) direction. When the OR between the original alpha-Mg and (3-Li is closer to the Burgers OR, more alpha PB '-Mg with the same orientation as the original alpha-Mg precipitate, which generates a strong variant selection for alpha M'-Mg that follows the Burgers OR. These alpha M'-Mg preferentially precipitate when they share common (1120) direction with alpha'-Mg that deviate from the Burgers OR to minimize overall strain. With increasing solid solution time, the increased alpha M'-Mg that deviate from the Burgers OR reduces deformation compatibility across phase boundaries, leading to diminished ductility.

Friction stir processing is an effective solid-state route for tailoring the microstructure and mechanical performance of dual-phase Mg–Li alloys, yet the evolution of phase coordination and interface behavior under different processing conditions remains insufficiently understood. In this work, a Mg-7.8Li-0.7Zn-0.4Sr-0.4Ca alloy was friction stir processed at different rotation speeds to establish the process–microstructure–property relationship. The grain size in the stir zone exhibited a non-monotonic dependence on rotation speed, and the optimum ultrafine-grained structure was obtained at 800 rpm, where the average grain sizes of α-Mg and β-Li were refined to 3.01 and 3.71 μm, respectively. The optimized sample achieved an ultimate tensile strength of 210 MPa and an elongation of 17.9%. The refined structure was stabilized by nanoscale MgZn2 precipitates, whose thermal stability was enhanced by Ca and Sr co-segregation, thereby exerting an effective Zener pinning effect during FSP. In addition, a rare deformation-induced FCC-β-Li phase was identified in the stir zone, indicating a BCC→FCC transformation under severe thermomechanical conditions. TKD analysis further showed that ultrafine α grains preferentially nucleated at triple junctions and α/β interfaces following the Burgers orientation relationship with the β matrix, and that selected variants formed at these sites. These mechanisms reduced interfacial energy, relieved local residual stress, and improved strain compatibility between the HCP α phase and the BCC/FCC β phase. Together with texture softening, they promoted coordinated deformation and led to an enhanced strength–ductility balance. This study provides a practical strategy for producing high-performance dual-phase Mg–Li alloys through synergistic regulation of grain refinement, precipitate stabilization, phase transformation, and variant selection.

This study systematically investigates the coordinated control of microstructure and mechanical properties in 7A09 aluminum alloy through the integration of cryogenic rolling and peak aging treatment, elucidating the underlying structure-activity relationships governing the process-structure-performance paradigm. A multi-scale characterization approach, incorporating EBSD, TEM, and mechanical testing, was employed. The mechanical results demonstrate a non-monotonic relationship between rolling reduction and alloy strength, characterized by an initial increase followed by a subsequent decrease. Optimal strength is achieved at 60% deformation (R60), where dislocation strengthening predominates, yielding a UTS of 654 MPa and EL of 9.5%. Conversely, excessive deformation (80%, R80) promotes the precipitation of micron-scale acicular Fe-rich constituents along grain boundaries. This microstructural evolution induces a mixed-mode fracture behavior, consequently diminishing the alloy's strength. Following peak aging treatment, the R60 alloy (designated RA60) exhibits significantly enhanced properties, attaining a UTS of 749 MPa and EL of 11.3%. This substantial strength improvement is attributed to the high-density precipitation of eta/eta' strengthening phases. These nano-scale precipitates effectively impede dislocation motion via the Orowan bypass mechanism, thereby augmenting dislocation slip resistance. Concurrently, the observed plasticity enhancement stems from reduced dislocation density and the formation of second-phase particles during aging, which mitigate potential microcrack nucleation sites. These findings collectively establish the key mechanisms governing strength-ductility synergy in cryogenically rolled aluminum alloys.

Achieving high strength, high ductility, and tension-compression yield symmetry in Mg alloys is fundamentally limited by the strong critical resolved shear stress (CRSS) anisotropy of hexagonal close-packed (hcp) Mg and the resulting slip-twin imbalance. Here we develop an extruded Mg-3Li-3Zn-0.5Y (LZ33-0.5Y) alloy that exhibits high tensile ductility (22.3%) and near-symmetric yielding (190 MPa in tension and 196 MPa in compression). To elucidate the governing deformation mechanisms, we employ a quantitatively coupled framework integrating in situ synchrotron X-ray diffraction, electron backscatter diffraction (EBSD), molecular dynamics (MD), and viscoplastic self-consistent (VPSC) modeling. Li addition reduces the c/a ratio to 1.615 and, more critically, markedly diminishes the CRSS anisotropy between basal and non-basal slip systems. MD simulations reveal that the ratios sigma Prismatic CRSS /sigma Basal CRSS and sigma Pyramidal CRSS /sigma Basal CRSS decrease by nearly one order of magnitude relative to pure Mg. Incorporating these CRSS ratios into VPSC yields slip-activity trends consistent with the experimentally observed and nearly synchronous lattice-strain evolution of basal and prismatic related reflections during in situ loading. The reduced CRSS anisotropy promotes extensive multiple-slip activity and produces similar early-stage deformation under tension and compression, accounting for the yield symmetry. Furthermore, the pronounced double-peak strain-hardening response in compression is quantitatively attributed to the sequential activation of {1012} tensile twinning followed by extensive twin transmission enabled by high geometric compatibility (m '), highlighting strain compatibility as a governing criterion beyond Schmid's law.

The Mg-6Gd-5Y-1Zn-0.4Zr alloy was prepared via centrifugal casting followed by homogenization, hot rolling, and aging treatment. The as-cast microstructure comprises equiaxed alpha-Mg grains with block-shaped 18 R long-period stacking ordered (LPSO) phases distributed along grain boundaries and lamellar 14H-LPSO phases within grain interiors. Homogenization treatment results in the complete dissolution of the 18R-LPSO phases into the alpha-Mg matrix. Hot rolling induces the formation of fine dynamic recrystallization (DRX) grains along kinked 14H-LPSO phase boundaries, developing a characteristic bimodal microstructure. The peak-aged alloy processed with 60 % rolling reduction demonstrates ultimate tensile strength (UTS) of 435 MPa, yield strength (YS) of 411 MPa, and elongation (EL) of 3.0 %, representing 88.3 % and 149.1 % enhancements in UTS and YS respectively compared to the homogenized state. The aged material maintains a damping capacity of 0.021, merely 0.005 lower than the as-cast condition. This optimal combination of strength and damping capacity originates from the synergistic effects of the bimodal microstructure and preserved 14H-LPSO phases. The microstructure analysis shows that in the Mg-6Gd-5Y-1Zn-0.4Zr ring component, the grain refinement strengthening and beta' precipitation strengthening constitute the main strengthening mechanism, and the alloy damping mechanism is the dislocation damping mechanism.

The Mg-8Gd-3.5Y-1.5Zn-0.8Mn (wt%) alloy was designed and prepared to investigate the synergistic dynamic recrystallization (DRX) mechanism at high temperature and low strain rate. We studied DRX process at different strain rates and temperatures, and revealed the corresponding mechanisms. The results show that at a low strain rate of 0.01 s-1 and 723 K, the grain size significantly decreases compared to 623 K, the grain boundaries protrude outward, and new small grains are generated. Quantitative calculations indicate that the thermal deformation mechanism can be reflected by the dissipation efficiency factor eta. As the value of eta increases, the dynamic softening mechanism shifts from dynamic recovery (DRV) to DRX. When the value of eta is greater than 0.36, under these conditions, continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) occur. This is because dislocation slip is hindered at grain boundaries, leading to dislocation entanglement and rearrangement, promoting the formation of low angle grain boundaries (LAGBs). As the deformation process progresses, the dislocation density of LAGBs continues to increase, reaching the critical point of promoting DRX. On the one hand, the high dislocation density region can serve as a nucleation site for DRX, and on the other hand, its characteristic of high strain storage energy is the driving force for CDRX nucleation. With the occurrence of CDRX, LAGBs gradually transform into high angle grain boundaries (HAGBs). CDRX provides nucleation sites for DDRX, and the outward protruding grain boundaries promote dynamic recrystallization nucleation. The distortion energy difference between the new grains and the surrounding matrix promotes the continuous movement of LAGBs, ultimately leading to the growth of crystal nuclei and the formation of recrystallized grains. The results indicate that controlling the hot working conditions can improve the microstructure of the alloy through recrystallization, thereby developing high-strength magnesium alloys.

Achieving high strength-ductility synergy has been a significant challenge in Mg alloys. In this study, we have found that adding traces of Sn can effectively improve ductility and maintain high strength in Mg alloys. The results indicate that the peripheral area of Mg-0.4Al-0.3Ca-0.2Mn-0.1Sn alloy exhibits a yield strength (YS) of 344 MPa, an ultimate tensile strength (UTS) of 382 MPa, and a high fracture elongation (FE) of 14.6 % after rotary swaging (RS) process. High strength is caused by the combined effects of grain refinement, abundant dislocations, and nano-scaled precipitated phases, with grain refinement being the most dominant factor. Average grain sizes are estimated to be 1.82 mu m in the central area and 1.78 mu m in the peripheral area, respectively. The introduction of trace amounts of Sn facilitates the formation of CaMgSn precipitates with nanometer size, which can enhance strength by pinning dislocation. The superior ductility is further attributed to the suppression of basal slips, and the activation of prismatic and pyramidal slips. Furthermore, adding traces of Sn notably reduces the maximum intensity of the {0001} texture from 35.65 mrd to 15.42 mrd, thereby improving the ductility of the alloy. These findings offer novel insights into the development of high-performance, low-weight, and low-cost Mg alloys for industrial applications.

The gradient structure was engineered within dual-phase LZ91 alloy sheets utilizing the ultrasonic surface rolling process (USRP), with a thorough examination of its influence on microstructural evolution, along with the mechanical and corrosion. The outcomes from the tensile experiments reveal that the synergistic improvement in both plasticity and strength of the LZ91 alloy can be achieved through the increasing gradient structural layers. In comparison to the untreated sample, the surface hardness (100.5 HV), yield strength (187 MPa), and ultimate tensile strength (203 MPa) of the USRPed sample exhibited increases of 96 %, 64 %, and 33 %, respectively, while still maintaining an impressive elongation of 34.7 %. For the first time, the organizational evolution of the beta-Li phase at different depths from the machined surface was meticulously investigated using an electron backscatter diffraction (EBSD), which remains unaccomplished in existing studies. The findings indicate that grain refinement, coupled with a high density of dislocations within the beta-Li phase, plays a pivotal role in enhancing the mechanical properties of the entire alloy. At the same time, the remarkable plasticity is predominantly ascribed to the gradient structure, which facilitates the avoidance of stress concentrations during the tensile process. Additionally, the USRP technique transforms residual surface stresses from initial tensile states into compressive states, concurrently reducing surface roughness-factors that collectively enhance corrosion resistance. In our study, the implementation of a gradient structure within a dual-phase Mg-Li alloy, achieved through a straight forward and economically efficient technique, offers profound insights into the attainment of exceptional synergistic mechanical properties alongside commendable corrosion resistance.

>Magnesium (Mg) and its alloys have been identified as one of the most promising structural, energy and biomaterials owing to their exceptional combination of properties. These include low density, high specific strength, good damping,high castability, high capacity of hydrogen storage, high theoretical specific capacity of batteries, good biocompatibility,and elastic modulus close to natural bone [1,2]. A total of3,919 papers in the field of Magnesium materials were published and indexed in the database of the“Web of Science Core Collection”in 2024 after the refined retrieval, based on a literature search on January 1, 2025.