Regional Deformation Research Articles

A Study on the Effect of Plastic Strain on Magnetic Phenomenology and Microstructure

The present work aspires to contribute to the discussion on the relationship between macroscopic measurements and microstructure, helping establish a methodology that will allow the quantitative assessment of the effect of strain on magnetic properties in the plastic deformation regime. In particular, we study the effect of strain on the magnetization process as a result of varying the anisotropy profile at the grain level. Results on micromagnetic calculations of hysteresis loops for various configurations of magnetic anisotropy are shown and discussed against the interplay between the energy terms involved in the calculations, namely anisotropy, demagnetizing, and exchange. The results are in line with previously obtained results using vector Preisach modeling with the Stoner–Wohlfarth model acting both as a switching and rotation mechanism. The hysteresis loop phenomenology is consistent with the emergence of a hard phase in the form of a boundary around soft grains which is assumed to be the result of the onset of compressive stresses in the plastic region. Future research will be oriented toward the study of the effect of the secondary peak in differential permeability, which is observed experimentally in the plastic deformation region, and its dependence on the angle of misalignment between the hard boundary and the soft grain.

Subscale modeling of material flow in orthogonal metal cutting

Enhanced simulation capability for the cutting process is crucial to making quick evaluations of cutting forces and temperatures, which are significant for assessing the machinability of the workpiece material and predicting tool wear. In this paper, the material flow in orthogonal cutting, including primary and secondary shear zones, is represented by a viscous/viscoplastic model that includes the temperature-sensitive Johnson-Cook flow stress model. A stabilized staggered finite element procedure is developed to handle incompressible Navier-Stokes material flow in combination with convection-dominated hardening and thermomechanical interaction. To handle material flow at tool-workpiece contact, a mixed method is used to reduce spurious oscillations in contact stresses along with simplified heat transfer in the tool-workpiece interface. A novel feature is that the velocity field is resolved as a subscale field to the velocity field of the distributed primary zone deformation model. It appears that the finite element solution to the subscale material flow model is significantly more cost-effective in contrast to directly addressing the velocity field and compared to the chip-forming simulations (DEFORM 2D). The cutting forces, temperature, and stress-strain state of the material in the critical deformation regions can be accurately estimated using the subscale model. The results obtained show that the trend of the estimated forces and temperatures is consistent with our experimental measurements, the DEFORM 2D simulations, and the experimental data from the literature.

Identification and Analysis on Surface Deformation in the Urban Area of Nanchang Based on PS-InSAR Method

Interferometric Synthetic Aperture Radar (InSAR) technology has emerged as a vital tool for monitoring surface deformation due to its high accuracy and spatial resolution. With the rapid economic development of Nanchang, extensive infrastructure development and construction activities have significantly altered the urban landscape. Underground excavation and groundwater extraction in the region are potential contributors to surface deformation. This study utilized Sentinel-1 satellite data, acquired between September 2018 and May 2023, and applied the Permanent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) technique to monitor surface deformation in Nanchang’s urban area. The findings revealed that surface deformation rates in the study area range from −10 mm/a to 6 mm/a, with the majority of regions remaining relatively stable. Approximately 99.9% of the monitored points exhibited deformation rates within −5 mm/a to 5 mm/a. However, four significant subsidence zones were identified along the Gan River and its downstream regions, with a maximum subsidence rate reaching 9.7 mm/a. Historical satellite imagery comparisons indicated that certain subsidence areas are potentially associated with construction activities. Further analysis integrating subsidence data, monthly precipitation, and groundwater depth revealed a negative correlation between surface deformation in Region A and rainfall, with subsidence trends aligning with groundwater level fluctuations. However, such a correlation was not evident in the other three regions. Additionally, water level data from the Xingzi Station of Poyang Lake showed that only Region A’s subsidence trend closely corresponds with water level variations. We conducted a detailed analysis of the spatial distribution of soil types in Nanchang and found that the soil types in areas of surface deformation are primarily Semi-hydromorphic Soils and Anthropogenic Soils. These soils exhibit high compressibility, making them prone to compaction and significantly influencing surface deformation. This study concludes that localized surface deformation in Nanchang is primarily driven by urban construction activities and the compaction of artificial fill soils, while precipitation also has an impact in certain areas.

The Influence of Fresh Latex Coagulation on the Parameter Characteristics of the Yeoh Hyperelastic Constitutive Model for Natural Rubber.

The coagulation of fresh latex is one of the critical processes that impacts rubber quality during natural rubber processing. Constitutive relationships are the basis for the study of the mechanical properties of rubber materials and serve as a prerequisite for material simulation studies. However, studies on the effect of different coagulation methods on natural rubber constitutive relationships have yet to be carried out, and the current models used for natural rubber constitutive relationships need to be improved. In order to investigate the effects of different coagulation methods on the hyperelastic properties of natural rubber, the impact of natural coagulation, enzyme coagulation, acid coagulation, microbial coagulation, and enzyme-assisted microbial coagulation on the hyperelastic constitutive relationship of natural rubber were analyzed in detail based on tensile experiments and the Yeoh model. The results show that after introducing a strain rate-related factor, the Yeoh model can describe well the mechanical behavior of natural rubber carbon black composites in different deformation regions, and the rubber, studied with varying coagulation methods, exhibits different mechanical properties in different deformation regions. This study provides new evidence for the study of high-performance natural rubber and serves as a reference for process selection in the primary processing of natural rubber.

Cold Deep Over Hot Shallow Crust: A Peculiar Metamorphic Architecture in the Neoarchean Metasedimentary Pontiac Subprovince, Superior Craton (Canada)

ABSTRACTThe Neoarchean Era is a key period in Earth's history as it witnessed a significant pulse of crustal formation corresponding to the assembly of several cratons, potentially coeval with a transition in the global tectonic regime. Neoarchean metasedimentary subprovinces of the Superior Craton, the largest unreworked Archean craton on Earth, were formed shortly before its final assembly and cratonization, thus providing valuable insights into the tectonic style, thermal state and architecture prevailing during this key period. Among these, the Pontiac Subprovince is one of the most studied, yet has a largely debated geodynamic history. In its northern extent, metamorphosed turbiditic sequences display a southward succession of index minerals—biotite, garnet, staurolite, kyanite and sillimanite—that may be indicative of a Barrovian‐like metamorphic gradient. However, the origin and evolution of this apparent gradient and its link to Neoarchean tectonics remain unclear. New mapping of metamorphic isograds and zones, petrological and microstructural analyses, whole rock and mineral chemistry analyses and phase equilibria modelling are integrated to decipher the Pontiac Subprovince tectonothermal evolution. Our analysis indicates that the peak equilibrium assemblages from the garnet, staurolite and sillimanite/melt zones developed early to late relative to the main regional deformation event (D2) and its associated steeply dipping S2 schistosity. Garnet zone rocks recorded a burial‐heating path with peak P–T conditions at 8.1–8.2 kbar and 582°C–585°C, along a low T/depth ratio of ~20°C/km. In contrast, staurolite and sillimanite/melt zone rocks followed isobaric heating and isothermal decompression paths with peak P–T conditions at 5.9–6.1 kbar and 610°C–625°C and 6 kbar and 700°C, respectively, along a moderate T/depth ratio of ~30–33°C/km. Since there is clear D2 structural continuity across the metamorphic zones over ~12 km and metamorphism occurred pre‐ to post‐D2, we interpret that the diverse P–T paths and contrasting T/depth ratios likely represent a spatially heterogeneous thermal structure developed within a single coherent structural block during and shortly after the formation of the subvertical S2 schistosity. Such features are hardly compatible with either modern inverted or continuous Barrovian sequences—known for consistent P–T evolution paths and similar T/depth ratios—or with discontinuous sequences requiring diachronicity. Our findings therefore do not fully reconcile with the existing accretionary/collisional models for the Pontiac Subprovince, given differences in their predicted apparent thermal gradients, metamorphic evolution and structural patterns. Alternatively, our data more closely match predictions for a sagduction‐dominated vertical process, where high heat influx at the base of the crust causes pooling/diapiric ascent of voluminous S‐type plutons, bordered by sagging synclines. This process led to the development of steeply dipping tectonic fabrics and pre‐ to late‐kinematic mineral assemblages along diverse P–T paths at contrasting yet coeval T/depth ratios. Our study provides insights into the evolution of the southeastern Superior Craton and highlights the need to apply an integrated quantitative approach to decipher its thermal structure and constrain the likely geodynamic processes that operated in the Neoarchean.

Mechanistic insights into waterjet-guided laser grooving of silicon: Impact of ablation dynamics, oxide formation, and thermal stress

Waterjet-guided laser machining of silicon offers precision with minimal heat-affected zones (HAZs), but understanding the mechanisms behind laser-material interactions remains essential. This study first utilizes orthogonal experiments to reveal fundamental relationships between processing parameters (scanning cycle, laser fluence, scanning velocity, and waterjet pressure) on groove depth and the depth-to-HAZ ratio. These findings guide the in-depth investigation of laser-material mechanisms. The results indicate that the ablation rate decreases with increasing scanning cycles, a phenomenon primarily attributed to the different absorption rates of 532 nm laser light between silicon and silicon dioxide. This conclusion is supported by x-ray photoelectron spectroscopy(XPS) results, which reveal that the accumulation of silicon dioxide occurs as the scanning cycles increase. Additionally, a near-linear relation between the ablation rate and laser fluence is observed, as the ablated area is continuously exposed to high laser intensity regions. However, increasing laser fluence also leads to diminished processing quality due to greater thermal deformation in non-ablating regions. Last, increased scanning velocity is found to cause rougher surfaces, as insufficient heat diffusion leads to higher thermal stress and results in micro-crack formations. The results provide a detailed understanding of the laser-induced transformations in the material and highlight optimal conditions for reducing thermal damage while maintaining machining efficiency. This study advances the field of laser processing by offering insights into the mechanisms governing oxide formation, thermal cracking, and material deformation during silicon grooving, providing the foundation for future exploration of laser-material interaction dynamics.

The Northern Giona Fault Zone, a Major Active Structure Through Central Greece

The steep northern slopes of Giona Mt in central continental Greece are the result of an E-W normal fault dipping 35–45° to the north, extending from the Mornos River in the west to the village of Gravia in the east. This fault creates a significant elevation difference of approximately 1500 m between the northern Giona footwall and the southern Iti hanging wall. The footwall comprises imbricated Mesozoic carbonates of the Parnassos unit, which exhibit large-scale drag folding near and parallel to the fault. The hanging wall comprises deformed sedimentary rocks of the Beotian unit and tectonic klippen of the Eastern Greece unit, forming a southward-tilted neotectonic block with subsidence near the Northern Giona Fault and uplift near the Ypati fault to the north. These two E-W faults represent younger structures disrupting the older NNW-trending tectonic framework. Fault scarps are observed all along the 14 km length of the Northern Giona fault accompanied by cataclastic zones, separating the carbonate formations of the Parnassos Unit from thick scree, slide blocks, boulders and olistholites. Inversion of fault-slip data has shown a mean slip vector of 45°, N004°E, which aligns with the current regional extensional deformation of the area, as confirmed by focal mechanism solutions. Based on the general asymmetry of the alpine units in the hanging wall, we interpret a listric fault geometry at depth using slip-line analysis and we forward modelled a disrupted fault-propagation fold using kinematic trishear algorithms, estimating a total displacement of 6500 m and a throw of approximately 2000 m. Seismic activity in the area of the Northern Giona Fault includes a magnitude 6.1 earthquake in 1852, which caused casualties, rockfalls and extensive damage, as well as a magnitude 5.1 event in 1983. The expected seismic magnitude is deterministically estimated between 6.2 and 6.7, depending on the potential westward continuation of the Northern Giona Fault beyond the Mornos River to the Northern Vardoussia saddle. The seismic hazard zone includes several villages located near the fault, particularly on the hanging wall, where intense landslide activity during seismic events could result in severe damage to regional infrastructure. The neotectonic development of the Northern Giona Fault highlights the importance of extending seismotectonic research into the mountainous regions of central Greece within the alpine formations, beyond the post-orogenic sedimentary basins.

Study on Soil Freeze–Thaw and Surface Deformation Patterns in the Qilian Mountains Alpine Permafrost Region Using SBAS-InSAR Technique

The Qilian Mountains, located on the northeastern edge of the Qinghai–Tibet Plateau, are characterized by unique high-altitude and cold-climate terrain, where permafrost and seasonally frozen ground are extensively distributed. In recent years, with global warming and increasing precipitation on the Qinghai–Tibet Plateau, permafrost degradation has become severe, further exacerbating the fragility of the ecological environment. Therefore, timely research on surface deformation and the freeze–thaw patterns of alpine permafrost in the Qilian Mountains is imperative. This study employs Sentinel-1A SAR data and the SBAS-InSAR technique to monitor surface deformation in the alpine permafrost regions of the Qilian Mountains from 2017 to 2023. A method for spatiotemporal interpolation of ascending and descending orbit results is proposed to calculate two-dimensional surface deformation fields further. Moreover, by constructing a dynamic periodic deformation model, the study more accurately summarizes the regular changes in permafrost freeze–thaw and the trends in seasonal deformation amplitudes. The results indicate that the surface deformation time series in both vertical and east–west directions obtained using this method show significant improvements in accuracy over the initial data, allowing for a more precise reflection of the dynamic processes of surface deformation in the study area. Subsidence is predominant in permafrost areas, while uplift mainly occurs in seasonally frozen ground areas near lakes and streams. The average vertical deformation rate is 1.56 mm/a, with seasonal amplitudes reaching 35 mm. Topographical (elevation; slope gradient; aspect) and climatic factors (temperature; soil moisture; precipitation) play key roles in deformation patterns. The deformation of permafrost follows five distinct phases: summer thawing; warm-season stability; frost heave; winter cooling; and spring thawing. This study enhances our understanding of permafrost deformation characteristics in high-latitude and high-altitude regions, providing a reference for preventing geological disasters in the Qinghai–Tibet Plateau area and offering theoretical guidance for regional ecological environmental protection and infrastructure safety.

Seventeen Million Years of Episodic Volcanism Recorded Within the Geologist Seamounts: Implications for Tectonic Drivers of Intraplate Volcanism

AbstractUpwelling and decompression of mantle plumes is the primary mechanism for large volumes of intraplate volcanism; however, many seamounts do not correlate spatially, temporally, or geochemically with plumes. One region of enigmatic volcanism in the ocean basins that is not clearly attributable to plume‐derived magmatism is the Geologist Seamounts and the wider South Hawaiian Seamount Province (∼19°N, 157°W). Here we present new bathymetric maps as well as 40Ar/39Ar age determinations and major and trace element geochemistry for six remote‐operated vehicle recovered igneous rock samples (NOAA‐OER EX1504L3) and two dredged samples (KK840824‐02) from the Geologist Seamounts. The new ages indicate that volcanism was active from 90 to 87 Ma and 74 to 73 Ma, inferring that in conjunction with previous ages of ∼84 Ma, seamount emplacement initiated near the paleo Pacific‐Farallon spreading ridge and volcanism spanned at least ∼17 m.y. Geochemical analyses indicate that Geologist Seamount lava flows are highly alkalic and represent low‐degree partial mantle melts primarily formed from a mixture of melting within the garnet and spinel stability field. The ages and morphology inferred that the seamounts were likely not related to an extinct plume. Instead, we build upon previous models that local microblock formation corresponded to regional lithospheric extension. We propose that the microblock was bounded by the Molokai and short‐lived Kana Keoki fracture zones. Regional deformation and corresponding volcanism among the Geologist Seamounts associated with the microblock potentially occurred in pulses contemporaneous to independently constrained changes in Pacific Plate motion—indicating that major changes in plate vectors can generate intraplate volcanism.

Himalayan Leucogranites: An Experimental Petrology Perspective

The High Himalayan leucogranites (HHL) are produced by muscovite breakdown of a metapelitic source, at temperatures below 800 °C, with initial melt water contents of ~5–7 wt.%. The tourmaline-rich HHL variety is colder, possibly a fractionation product of the hotter two-mica HHL. HHL lack restites such as iron-rich garnet, which, when present, is Mn-rich, signaling fractionation processes. The low redox state of HHL mirrors that of their graphite-bearing source, yet there is evidence of a significant increase in fO2 during crystallization of some HHL. Their relationships with regional deformation call for late emplacement of the main bodies, which must have cooled at 3–4 kb to allow muscovite crystallization, which in turn imposes stringent constraints on unroofing rates of the collisional chain.

A novel hybrid SPH-DEM approach for simulating rockburst behavior in tunnel excavation

A hybrid smoothed particle hydrodynamics-discrete element method (SPH-DEM) is proposed to simulate rockburst behavior during deep tunnel excavation. Within this coupled code, the rock mass continuity stress and elastic deformation are computed by solving partial differential equations (PDEs) via the SPH method. Rock cracking is realized by the transition of SPH particles to DEM particles while considering rock damage. The noncontinuous deformation region is subsequently simulated via a DEM-based method. The contact pairs are established via a link-list algorithm, which enables point-to-point contact to simulate postfracture spalling. Additionally, the dormant particle approach is introduced within the continuous domain represented by SPH to simulate the excavation process, while the confining pressure application method is employed to maintain tunnel boundary stability. The coupling code accuracy and feasibility were demonstrated through three benchmark tests and three typical tunnel case studies. The results indicate that this hybrid method demonstrates clear physical significance, high robustness, and relatively less computational time consumption than standalone DEM code does, making it suitable for addressing practical tunnel-scale issues. In contrast to continuous methods, the proposed approach authentically simulates crack propagation and spalling without necessitating grid reconfiguration. Unlike discontinuous methods, the hybrid method handles the material as a continuous medium before fracturing, allowing for a detailed depiction of the stress and strain before and after failure.

Unraveling the genetic type and metallogenetic mechanism of the oldest uranium deposit associated with granitoid, South China: A comprehensive analysis of whole-rock geochemistry, and elemental and U-Pb isotopic signatures of uranium minerals

The Daliang deposit in the Motianling area of South China is unique for its synchronous uranium mineralization with regional metamorphism. To elucidate its genetic mechanism, whole-rock geochemistry from the Daliang deposit was undertaken, along with analyses of the chemical and isotopic signatures of minerals. The Motianling granitoids exhibit strongly peraluminous S-type affinities with low Th/U ratios, representing a uranium source for mineralization. Altered mineralogical and geochemical signatures of altered and ore samples indicate a multi-stage history after granitic emplacement: (1) Late magmatic-hydrothermal alteration characterized by greisenization, K-feldspathization, and propylitization; and (2) brittle-ductile deformation with uranium mineralization. Notably, ore-stage alteration mineral contains chlorite + quartz + sericite, which is consistent with the mineral assemblage of low-greenschist facies metamorphism. EMPA and LA-ICPMS dating on pitchblende yielded ages of 378 and 380 Ma, coinciding with the timing of regional ductile deformation. The pitchblende exhibits weak fractionation between LREEs and HREEs and negative Eu anomalies, mirroring characteristics observed in syn-metamorphic uranium deposits. Therefore, we suggest that uranium mineralization within the Daliang was related to crustal metamorphism, and the Daliang deposit belongs to syn-metamorphic deposit. Fluids likely have been liberated from the acidic brines-bearing Sibao Group that underwent low-greenschist facies metamorphism. Paleozoic intracontinental orogeny in South China resulted in brittle-ductile deformation in the Motianling pluton. These zones provided favorable pathways for the migration of ore-forming fluids and subsequent uranium mineralization. Late Devonian retro-metamorphism facilitated the percolation of oxidizing metamorphic fluids into the Motianling granitoids, circulating along the pre-existing brittle-ductile zones. This study presents the first evidence for syn-metamorphic uranium deposits within the granite of South China. This finding suggests potentially distinct mineralization mechanisms compared to traditional granite-related uranium deposits in the region, warranting further investigation.

Polyphase deformation history and its structural controls on auriferous quartz vein stockwork in the Xiaoqinling district, southern margin of the North China Craton

“Structural control” is a crucial point in revealing the genesis mechanism and distribution patterns of vein-type gold deposits. Being the second largest gold producer in China, the Xiaoqinling region has experienced complex and polyphase structural deformations. However, the persistent absence of research on the regional structural deformation sequences and superimposed relationships have posed significant challenges to understanding the ore-controlling structural model, timing of gold mineralization, and dynamic mechanisms. In this contribution, we established an Early Paleoproterozoic to Late Mesozoic structural deformational-event framework (D1–D5) and proposed an ore-controlling structural model by integrating an analysis of the geometry, kinematics, overprinting, and crosscutting relationships of structures at different deformation events, the spatial coupling relationship between gold veins and structures with various orientations, and prior geochronological data. The D1–D4 deformation structures initially established the EW–NW, NE and NS-oriented pre-existing ore-controlling structures framework. The reactivation of pre-existing structures (D1–D4) during the D5 deformation event (gold mineralization period), concurrently giving rise to new NE-trending extensional structures accompanying the tectonic evolution of the metamorphic core complex (MCC), collectively created a multi-directional structural network connecting mineralizing fluids to structural traps, within which auriferous quartz veins emplaced, and displaying a phenomenon of multi-directional intertwining. Combined with previous studies, new structural analysis showing that gold mineralization in the Xiaoqinling area falls within the Early Cretaceous, peaking at 126 Ma, aligning with the timing of rapid crustal uplift, generated in a backarc extension setting induced by the roll-back following the flat subduction of the Paleo-Pacific slab. Our study highlights the crucial role of reactivated pre-existing structures in controlling gold mineralization, demonstrating that structural deformation analysis is essential for understanding the genesis and mechanisms of complex gold district, and suggests that the ductile–brittle shear zones trending in both E–W and NE directions within the middle part of the Xiaoqinling district are crucial positioning areas for exploration of deep-seated gold deposits.

Far-field response to the closure of the Meso-Tethys Ocean: New geochronological evidence from the Chem Co graben in the westernmost part of Central Tibet

The Chem Co graben is located in the westernmost part of the Qiangtang block, central Tibet. It is adjacent to the Longmu Co Fault to the north and approximately 50 km away from the Karakoram Fault to the west. The formation of the graben resulted in the exposure of basement rocks in the footwalls of the graben bounding normal fault, which hold crucial information on the Mesozoic closure of the Meso-Tethys Ocean. Garnet-biotite schist crops out sporadically in the footwall of the graben-boundary normal fault, and is intruded by leucogranite dikes. Pseudosection modeling indicates peak metamorphic conditions for the schist of 590–670 °C and 4.5–7.5 kbar, similar to the conditions of mid-crustal rocks at the western end of the Qiangtang block. Field investigations and microstructural analysis suggest syn-kinematical left-lateral strike-slip in both the biotite schist and granitoid veins. Zircon U − Pb, monazite U − Th − Pb, and 40Ar/39Ar ages show that intense regional intensive tectonic deformation and contemporaneous magmatism began at ∼120.6 Ma and ended with the peak metamorphism conditions at 105.3 ± 6.0 Ma. These results indicate that the closure of the Meso-Tethys Ocean in the westernmost part of central Tibet occurred over this period (i.e., 121–105 Ma) with final closure during the late Early Cretaceous. The closure of the Meso-Tethys Ocean likely triggered widespread far-field responses, extending from the Altyn Tagh Fault to the Longmu Co Fault, and reaching the Pangong and Hunza regions around the Western Himalayan Syntaxes. Episodic crustal thickening and surface uplift since the closure of the Meso-Tethys Ocean caused the upper crust to be extruded along the westernmost part of central Tibet, leading to the formation of the Chem Co graben.

Effect of grain size gradient on the mechanical behavior of gradient nanograined pure iron: an atomic study

Abstract Using molecular dynamics simulation, the deformation mechanisms of gradient nanograined (GNG) pure iron (Fe) were investigated. Simulations of uniaxial tensile experiments were conducted on samples exhibiting different grain size gradients. The simulation results reveal the presence of a critical GNG parameter (g), at which point the GNG-Fe attains its highest strength. The deformation mechanisms of three representative samples, namely GNG-2 with the g value at the threshold, GNG-1 with a g value smaller than the critical threshold and GNG-4 with a g value exceeding it, were thoroughly investigated. Within the coarse-grained (CG) region of GNG-1, the primary deformation mechanism is predominantly characterized by planar defects, rather than being dominated by dislocations. Furthermore, the mechanisms of both ‘strain hardening’ and ‘softening’ were observed and discussed in this region. The deformation of the coarse grains occurs in a coordinated manner, and the magnitude of the back-stress is insufficient to trigger grain boundary (GB) motion in the fine-grained (FG) region. In contrast, the deformation of the CG region in the GNG-4 primarily depends on dislocation. The ‘hardening’ and ‘softening’ effects of the dislocations were described and discussed. In the FG region of GNG-4, the grains undergo deformation primarily through GB motion, a phenomenon attributed to the significant back-stress generated by the uncoordinated deformation exhibited by the coarse grains. In the CG area of sample 2 with the g value at threshold, both dislocation- and planar defects-controlled mechanisms are observed. In the FG of this sample, neither GB migration and grain rotation are found. Only the GB width becomes larger, indicating that the back-stress transferred from the CG area makes the GB more active, but not large enough to induce the GB migration or grain rotation. The results of this work may provide some theoretical supports for the deformation mechanism of the GNG materials.

Coseismic geodetic and geophysical variations detected for the January 19th, 2021 San Juan earthquake. Tectonic implications

The coseismic surface variations and crustal deformation in the Central Precordillera region of San Juan (Argentina) as a consequence of the Mw 6.5 earthquake of January 19th, 2021 (2:46 UTC) were characterized by a multidisciplinary team, integrating information from Gravity, Seismology, GNSS and DInSAR (Synthetic Aperture Radar Differential Interferometry) techniques.Prior to the occurrence of the event, several periodic measures were taken at fixed reference points throughout San Juan province. The results of the data analysis show significant changes in height corresponding to the uplifting of a few centimeters of the hanging wall block in accordance with the estimated deformation obtained by the focal mechanism. In addition, the transcurrent component is evident in the GNSS vectors calculated after the earthquake. These results are consistent with the Gravity variations measured at the control points. This indicates the uplifting of the basement of Central Precordillera while the elastic Andean compressional deformation migrates N-E related to the Tulum lineament. The joint analysis of 4D gravity with GNSS heights shows an accumulation of deformation involving the lower crust prior to the earthquake, and the release of stresses with permanent deformation, which partially complies with the laws of isostasy in the Precordillera, after the earthquake.

Mechanical behaviour and subsurface characteristics of Ti-6Al-4V subjected to electropulsing-assisted multiple laser shock processing impacts

Electropulsing (EP)-assisted laser shock peening (LSP), involving the synchronous application of EP and LSP to Ti-6Al-4V samples, represents an innovative surface strengthening technology. A comprehensive series of evaluations and examinations were conducted to thoroughly investigate the effects of EP-assisted multiple laser shock processing impacts on the mechanical behaviour and subsurface characteristics of the Ti-6Al-4V sample. The strength and ductility properties, fatigue performance, microstructure features in subsurface regions and deformation characteristics at various depths of the treated Ti-6Al-4V samples were investigated. The results revealed that as the number of impacts increased, a prominent multilayered structure, including a remelting layer, a severe plastic deformation region, and a plastic deformation-affected zone in the subsurface developed. The observed increase in strength can be attributed to grain refinement, an increase in dislocation density and the presence of high-density nanotwins within the subsurface layer. A high fatigue life was achieved by EP-assisted multiple LSP, with a ∼328.1 % increase compared with that of the as-received sample.The improvement in durability is mainly related to the enhanced subsurface structure acted as a barrier to crack propagation.

Thermo-mechanical response and form-stability of a fully metallic composite phase change material: Dilatometric tests and finite element analysis

Composite Phase Change Materials (C-PCMs), such as immiscible Al-Sn alloys are designed to store and release heat as a result of the phase transformation of one of the phases, i.e., Sn in this case. The volume changes induced by melting and solidification of the low-melting Sn phase as well as the different thermal expansion of solid Al and Sn phases induces stress fields during thermal cycles. Repeated experimental dilatometric tests were performed on the above C-PCM to check their microstructural stability as well as its effect on their form-stability, i.e., capability to recover the initial shape under various potential cyclic service conditions.Analysis of the thermo-mechanical behaviour of the two phases, as well as the overall one, have been investigated under the simple thermal profiles reproducing dilatometric tests. A finite element model of fully dense Al-Sn C-PCM, where a single spherical inclusion of Sn is surrounded by Al matrix, is generated and numerical thermo-mechanical analysis is performed. The thermal-dependence of elastoplastic-behaviour, thermal expansivity and other thermophysical properties of the 2 solid phases has been modelled, together with compressibility of liquid Sn. The simulations illustrate the overall material behaviour as well as the local thermomechanical response. The results for the slopes of elongation vs temperature curves agree well with experimental data from dilatometric tests, for which form-stability is observed from the third cycle. The results also suggested that the plastic deformation of the only regions of Al phase surrounding the Sn inclusion accommodates its expansion during heating and melting. In these latter regions, at the end of a dilatometric cycle, compressive strain in radial direction reaches a maximum value of 0.1 %, higher than overall strains.

Achieving superior ductility with ultrahigh strength via deformation and strain hardening in the non-recrystallized regions of the heterogeneous-structured high-entropy alloy

Developing metallic structural materials with ultrahigh strength and exceptional ductility remains a significant challenge due to the trade-off between both properties. This study presents a heterogeneous-structured high-entropy alloy achieving a superior combination of strength and ductility compared to the reported heterogeneous-structured high entropy alloys through deformation and strain hardening in the non-recrystallized regions. The cold rolling followed by annealing at 760 °C resulted in a heterogeneous microstructure consisting of a small fraction of ultrafine recrystallized grains and extensive non-recrystallized regions, with a significant amount of L12 precipitates throughout the alloy. The architected microstructure led to a significant enhancement of yield strength through mechanisms including dislocation strengthening, L12 strengthening, and grain boundary strengthening. During the deformation, the non-recrystallized regions accommodated substantial strain through the reactivation of pre-existing deformation bands and the synergistic deformation of the FCC and L12 phases, thereby markedly enhancing ductility. Moreover, the metastable FCC matrix underwent FCC→BCC phase transformation, leading to the formation of numerous short-range BCC domains, which further contributed to the pronounced strain hardening. Consequently, the alloy annealing at 760 °C achieved a yield strength of 1.73 GPa, an ultimate strength of 2.05 GPa, and an elongation of 21.0 %. This study underscores a novel strategy for the concurrent enhancement of strength and ductility and provides valuable insights for the design of high-performance alloys.

Automated cell tracking using 3D nnUnet and Light Sheet Microscopy to quantify regional deformation in zebrafish.

Light Sheet Microscopy (LSM) in conjunction with embryonic zebrafish, is rapidly advancing three-dimensional, in vivo characterization of myocardial contractility. Preclinical cardiac deformation imaging is predominantly restricted to a low-order dimensionality image space (2D) or suffers from poor reproducibility. In this regard, LSM has enabled high throughput, non-invasive 4D (3d+time) characterization of dynamic organogenesis within the transparent zebrafish model. More importantly, LSM offers cellular resolution across large imaging Field-of-Views at millisecond camera frame rates, enabling single cell localization for global cardiac deformation analysis. However, manual labeling of cells within multilayered tissue is a time-consuming task and requires substantial expertise. In this study, we applied the 3D nnU-Net with Linear Assignment Problem (LAP) framework for automated segmentation and tracking of myocardial cells. Using binarized labels from the neural network, we quantified myocardial deformation of the zebrafish ventricle across 4-6 days post fertilization (dpf). Our study offers tremendous promise for developing highly scalable and disease-specific biomechanical quantification of myocardial microstructures.