High Homogenization Temperatures Research Articles

Solidification of Ni-Mn-Ga magnetic shape memory alloy built via laser powder bed fusion on a single crystal substrate

Ni-Mn-Ga-based magnetic shape memory (MSM) alloys have significant potential as fast actuation materials due to their ability to undergo large magnetic-field-induced strains in an external applied magnetic field. This study explored the manufacture of Ni-Mn-Ga via the laser powder bed fusion (PBF-LB/M) additive manufacturing process, aiming to determine the parameter combinations that enhance the development of a crystallographically oriented coarse grain structure. In the first part of the study, the single tracks were melted on pre-heated single-crystalline Ni-Mn-Ga substrates by varying the applied laser power and scanning speed. This experiment revealed the existence of a parameter window where epitaxial solidification of the single-track can be achieved. Additionally, the results demonstrated that preheating prevents cracking of the single-crystal substrate. Subsequent experiments using a thin-walled 3D geometry demonstrated that this epitaxial structure was replicated across multiple layers, with the built samples exhibiting crystallographically oriented oligocrystalline structures following a high-temperature homogenization treatment. PBF-LB/M shows high potential for facilitating the additive manufacturing of oriented coarse grain oligocrystals for the production of microscale actuators.

Reconstructing fluid evolution and precipitation mechanism of the Chuankeng skarn copper deposits, China: New insight from microthermometry and LA-ICP-MS analysis of fluid inclusions

Skarn deposits are significant sources of copper, yet there are different understandings on their fluid evolution and precipitation mechanism due to lack of direct constraints on fluid compositions of mineralization process. Here, we present a detailed reconstruction of fluid evolution history from the pre-ore prograde stage through the syn-ore retrograde stage to the post-ore stage of the Chuankeng deposit in the North Wuyi area, South China, based on fluid inclusion microthermometry and LA-ICP-MS analysis of typical minerals from three stages. The pre-ore fluids trapped in pyroxene have higher homogenization temperatures (450–550 ℃), higher salinities (31.9–51.5 wt% NaCl equiv), but lower concentrations of Cu (∼556 ppm) than syn-ore fluids (338–465 ℃, 31.3–38.9 wt% NaCl equiv, ∼3247 ppm Cu). The post-ore fluids show lower temperatures (139-163℃), salinities (1.1–6.5 wt% NaCl equiv), and low concentrations of Cu (<387 ppm). Fluids of all paragenetic stages have high K/Na and Rb/Na ratios, exhibiting signatures of magmatic hydrothermal fluids. Mixing of the magmatic fluids with meteoric waters of lower temperature and salinity occurred at the final post-ore stage, thus it is not related to Cu mineralization. As the temperature descends from 445 ℃ to 340 ℃, the Cu/(Na + K) ratios of syn-ore fluids diminish exponentially, manifesting fluid cooling within a certain temperature may be an important factor controlling Cu mineralization. Concomitantly, a moderate negative correlation between the Ca/(Na + K) ratios and Cu/(Na + K) ratios of syn-ore fluids suggests that fluid-rock interaction do have some impact on copper contents. Additionally, the Cu/(Na + K) ratios of syn-ore fluids in quartz are an order of magnitude higher than those of pre-ore fluids, and it is proposed that during the initial retrograde stage—the onset of mineralization—the magma chamber released fluid pulse with higher copper contents. Based on these findings, the fluids of pre-ore prograde stage and syn-ore retrograde stage are distinct magmatic fluid pulses, and copper-rich fluids, thermal cooling within a specific temperature range and fluid-rock reaction are suggested to be key factors controlling metal enrichment in skarn copper systems.

Genesis of a sediment-hosted vein-type Cu deposit in the Lanping Basin, SW China: New insights from geology and LA–ICP–MS analysis of fluid inclusions

Sediment-hosted Cu deposits, including stratiform and epigenetic vein-type Cu deposits, are the second largest source of Cu worldwide. However, many facets of these vein-type Cu deposits, such as the nature and origin of ore fluids and geodynamic mechanisms that produced these fluids, remain controversial, limiting our interpretations of the ore genesis and hampering the selection of exploration strategies. Numerous sediment-hosted vein-type Cu deposits are present in the Lanping Basin, SW China, of which the Jinman deposit is the largest. Copper orebodies at Jinman consist of Cu-sulfide–quartz–carbonate veins and altered wall-rocks hosted mainly in faults and fracture zones in metamorphosed and deformed clastic rocks. The deposit was formed in three stages, pre-, syn- and post-ore, with the first two stages producing hydrothermal veins. The veins in pre-ore stage consist of quartz + ankerite ± sericite ± pyrite, whereas those in syn-ore stage consist of Cu-sulfides + quartz + carbonate ± sericite. During the syn-ore stage, tennantite, quartz, and ankerite crystallized early, then bornite was precipitated, followed by chalcopyrite and chalcocite and finally calcite. Only minor sericite was formed during the post-ore stage. Two major types of fluid inclusions—CO2-rich and aqueous inclusions—are present in both pre- and syn-ore quartz, whereas only aqueous inclusions are present in syn-ore calcite. In pre- and syn-ore quartz and calcite, CO2-rich inclusions have higher homogenization temperatures (275–323 °C) and pressures (307–3495 bar) and lower salinities (0.22–2.7 wt% NaCl eqv.) than aqueous inclusions (164–299 °C, 6.5–80.4 bar and 3.7–20.9 wt% NaCl eqv.). However, the small variations in Cs/Na and Cs/(Na + K) ratios [log Cs/Na = –3.3 ∼ –1.9, log Cs/(Na + K) = –3.3 ∼ –2.1] of the fluid inclusions suggest a same source for the ore fluids. We propose that during both stages, CO2-rich inclusions resulted from unmixing of initial deep-seated, single-phase CO2-rich fluids, whereas aqueous inclusions likely represent the fluids that evolved from these unmixed fluids by extensive CO2 degassing. This interpretation, combined with microthermometric results of CO2-rich inclusions, suggests a mesothermal, low-salinity H2O–NaCl–CO2 ore fluid system. The fluid inclusions from Jinman have similar compositions to those of metamorphic fluids, suggesting a metamorphic origin for the ore-forming fluids. The evolution of fluid compositions suggests that fluid degassing likely acted as a major mechanism for Cu precipitation. We propose that the ore fluids were generated through metamorphic devolatilization of basement of the Lanping Basin in the Biluoxueshan–Chongshan metamorphic zone under a compressional or transpressional regime caused by Cenozoic India–Asia collision. The Jinman deposit has many similarities to orogenic gold deposits worldwide and thus can be thought of as an orogenic deposit. Based on a compilation of the geological characteristics of global sediment-hosted epigenetic vein-type Cu deposits, we suggest that other sediment-hosted epigenetic vein-type Cu deposits with similar genesis to the Jinman deposit are likely present in other regions worldwide. This highlights the exploration potential of this type of deposit in these regions and the need for further research.

Mechanism of improving solidification structure of super austenitic stainless steel by feeding strip into molten steel

Feeding steel strip into molten steel is an effective technique for refining the solidification structure of steel, especially for high-alloy steel. This study experimentally and numerically investigated the effects of feeding strip on the solidification structure of super austenitic stainless steel S32654. The results revealed that feeding strip noticeably increased the proportion of equiaxed grains, refined the dendritic structure, and improved Mo segregation and the precipitation of σ phase. The relevant mechanism was clarified as follows. Firstly, feeding strip promoted the formation and survival of a large number of floating dendrites by cooling the molten steel. As the temperature decreased, these floating dendrites sharply increased their quantity by repeated splitting and then acted as nucleation particles. Numerous equiaxed grains grew around these floating dendrites, significantly refining the central dendritic structure. Meanwhile, the doubling of the equiaxed grains has two effects on Mo segregation. First, it prevented the growth of columnar grains and the movement of Mo segregation interface towards the center, thus reducing the Mo macrosegregation. On the other hand, it dispersed and refined the residual liquid phase (Mo segregation regions), thereby reducing the Mo microsegregation. Additionally, the reduced Mo segregation lowered the σ phase precipitation temperature, allowing it to form in solid austenite with a shortened growth duration. The lighter Mo segregation and slower Mo diffusion in solid austenite led to insufficient Mo supply for the σ phase growth. Moreover, dendritic refinement limited the growth space of the σ phase. Finally, less and finer σ phase particles precipitated in the S32654 steel fed with strip. The improvement of feeding strip on the solidification structure will reduce the temperature and time required for high-temperature homogenization, which is beneficial for the subsequent hot working.

Structure and properties of samples made from XH50BMTJuB-VI (EP648-VI) alloy produced by using selective laser melting process

The paper presented examines the composition, the structure and properties of samples made from the XH50VMTJuB-VI (hereinafter EP648-VI) alloy obtained by using the selective laser melting process (the SLM-process) in relation to manufacturing parts for aviation purposes. The authors carried out a comparative study of the samples’ structure and properties upon conducting such operations as depositing in two directions (horizontal and vertical), separate heat treatment and after hot isostatic pressing (HIP) followed by a standard heat treatment process applied for deformable semi-finished products made from the XH50VMTJuB-VI(EP648-VI) alloy. The authors inform that the manufacturing of samples by means of the SLM-process involved powders obtained through the technology of the vacuum-induction spraying of the molten metal jet with an inert gas (argon). The paper has established that samples obtained by using the HIP process with the application of the heat treatment (a vacuum high-temperature homogenization followed by a long-term aging) demonstrated the best set of mechanical properties, since the implemented complex process ensured the “healing” of pores and discontinuities in the structure, and strengthening by means of the intermetallic g¢-phase, while separations of the excess, needle-shaped a -Cr phase are fine and evenly distributed in the material structure. The authors noted that mechanical properties of samples under analysis were generally in compliance with the requirements set forth in the regulatory documentation for deformable semi-finished products made from the XH50VMTJuB-VI (EP648-VI) alloy, while underlining the increase in the level of impact strength of samples that underwent the HIP process, and the long-term strength of samples manufactured in the vertical direction compared to other options studied. Following the results of the analysis, the authors established that the SLM-process made it possible to manufacture products whose level of mechanical properties was close to the level of the deformable material, and even exceeded it in some cases.

A microwave blackbody target for cosmic microwave background spectral measurements in the 10–20 GHz range

The Tenerife Microwave Spectrometer (TMS) is a ground-based radio-spectrometer that will take absolute measurements of the sky between 10–20 GHz. To ensure the sensitivity and immunity to systematic errors of these measurements, TMS includes an internal calibration system optimised for the TMS band, and cooled down to 4 K. It consists of an Aluminium core, composed of a baseplate and a bed of pyramidal elements coated with an absorber material and a metallic shield. The absorber coating is made of a commercial resin ECCOSORB CR/MF 117. To achieve the high stability (± 1 mK/h), temperature homogeneity (thermal gradients ΔT ≤ 25 mK), and emissivity (e ≥ 0.999) requirements of the reference unit, careful consideration has been given to the RF and thermal properties of the materials, as well as their geometry. In summary, this paper presents a comprehensive account of the design, characterisation, and test results of the TMS reference system.

Evolution of Ore-Forming Fluids at Azegour Mo-Cu-W Skarn Deposit, Western High Atlas, Morocco: Evidence from Mineral Chemistry and Fluid Inclusions

The Azegour Mo-Cu-W skarn deposit, located on the northern side of the Western High Atlas, occurs in lower Cambrian volcanic and sedimentary rocks. The mineralizations are linked to the hydrothermal alterations that affected carbonated layers of the lower Cambrian age during the intrusion of the calc-alkaline hyperaluminous Azegour granite. Four stages of the skarn and ore mineral deposition have been identified as follows. Firstly, (i) the early prograde stage and (ii) the late prograde stage. These prograde stages are characterized by anhydrous minerals (wollastonite, garnets, and pyroxenes) associated with scheelite mineralization. Based on mineral chemistry studies, the early prograde stage is dominated by andradite (Ad72.81–97.07) and diopside (Di61.80–50.08) indicating an oxidized skarn; on the other hand, the late prograde stage is characterized by a high portion of grossular (Gr66.88–93.72) and hedenbergite (Hd50.49–86.73) with a small ratio of almandine (Alm2.84–34.99), indicating “strongly reduced” or “moderately reduced” conditions with low f(O2). The next two stages are (iii) the early retrograde stage and (iv) the late retrograde stage, which contain hydrous minerals (vesuvianite, epidote, chlorite, muscovite, and amphibole) associated with sulfide. Fluid inclusions from pyroxene and quartz (prograde skarn stage) display high homogenization temperatures and high to low salinities (468.3 to &gt;600 °C; 2.1 to &gt;73.9 wt% NaCl equiv.). The boiling process formed major scheelite mineralization during prograde skarn development from dominated hydrothermal magmatic fluid solutions. By contrast, fluid inclusions associated with calcite–quartz–sulfide (retrograde skarn stage) record lower homogenization temperatures and low salinities (160 to 358 °C; 2.0 to 11.9 wt% NaCl equiv.). The distribution of the major inclusions types from the two paragenetic stages are along the trend line of fluids mixing in the salinity–homogenization temperature (magmatic water), illustrating the genesis of ore-forming fluid by mixing with fluids of low temperatures and salinities (metamorphic and meteoric waters).

A novel flow channel design to achieve high temperature homogenization in solid oxide fuel cell

The thermal stress, which has a significant impact on the stable and prolonged operation of Solid Oxide Fuel Cells (SOFCs), can be further aggravated by the presence of local hot spots. Improving the distribution uniformity of physical quantities is of great significance to improving the internal temperature distribution of the SOFC. In this study, to improve the uniformity of temperature distribution, the thermal and flow distribution of three kinds of flow fields are investigated including Z, U, and L flow fields. The results show that the temperature distribution is dominated by the flow rate distribution. To optimize the physical quantity distribution of the designed flow channel, a novel, and easy-to-manufacture thermal management is proposed. This method is to adopt the extended ridge for controlling the flow rate into each flow channel. Moreover, a multi-population genetic algorithm is adopted to optimize the length of each extended ridge. The optimized results show that the temperature deviation in the Z, U, and L flow fields are reduced by about 64.20 %, 26.06 %, and 23.45 % respectively. This novel thermal management method enables more uniform temperature distribution and it is expected to be used in large-scale manufacturing due to its simple but subtle design.

Geological conditions and controls on accumulation of tight sandstone gas, deep part of the Shengbei sub-sag, Turpan-Hami basin, NW China

With the further exploration of the Jurassic strata in the Turpan-Hami Basin, the targets for hydrocarbon exploration have been gradually shifted from the tectonic belts around sags to the proximal lithological zones of deep sags. Based on the systematic coring of the first exploration well (well Qintan-1) in the center Shengbei sub-sag, this study conducted experiments of organic carbon, pyrolysis, gas chromatography (GC), nuclear magnetic resonance (NMR), and low-temperature nitrogen adsorption. Then, this study systematically analyzed the geological conditions and major controlling factors for the accumulation of tight sandstone gas in the deep part of the Shengbei sub-sag. The results show that: (1) Multiple sets of coal-measure source rocks have developed in the Jurassic strata in the center Shengbei sub-sag, providing plenty of gas sources for multilayered hydrocarbon accumulation; (2) Tight sandstones have poor physical properties and complex pore structures. However, high-permeability zones and anomalous zones of nano-scale pores have developed in the deep part, providing favorable spaces for the accumulation and preservation of tight oil and gas in the deep part; (3) Compaction and late carbonate cementation are key factors in reservoir densification. The microscopic storage space and connectivity of the tight sandstone reservoirs in the Shengbei sub-sag were improved due to the dissolution of fluids in coal measure strata. The occurrence of high-quality reservoirs in the Shengbei sub-sag is significantly controlled by source rocks, and both the former and the latter are characterized by adjacent sources and reservoirs and short-distance migration and accumulation. Furthermore, the special geological phenomena of chert cementation, abnormally high homogenization temperatures of fluid inclusions, and abnormal pyrolysis parameters confirm the presence of low-temperature hydrothermal activity in the deep part of the target strata. Therefore, the center Shengbei sub-sag has geological conditions for the large-scale accumulation of primary gas and, thus, is a key area for future hydrocarbon exploration.

High-strength porous NiTi shape memory alloys with stable cyclic recovery properties fabricated using elemental powders

Based on previous research regarding the high-vacuum sintering of elemental powder (EP) NiTi alloys, this study investigates the preparation of high-strength, highly cyclically stable porous NiTi shape memory alloys. The microstructures, martensitic transformation behaviors, compressive and compressive recovery properties, and cyclic stabilities of the sintered and aged porous NiTi alloys were compared and analyzed. The porosity and average pore size increased with the addition of NaCl, with the oxygen content increasing slightly. The sintered alloy displayed an inhomogeneous distribution of the Ni4Ti3 precipitate, which exhibited a dispersed and homogeneous distribution after aging. The sintered porous NiTi alloy exhibited a multistage phase transformation. The martensitic transformation was suppressed after aging owing to changes in the size and distribution of the precipitates, and only R-phase transformation was observed. Porosity and aging precipitation influenced the dual yield points and recovery properties of porous NiTi. The pinning effect of aging precipitation increased the yield point and reduced the residual strain in the recovery. However, at a high porosity, the volume fraction of NiTi matrix decreased, resulting in a small strengthening contribution of precipitation. The disruption of porous structure was the dominant causes of irreversible strain. As the porosity increased, the porous structure became increasingly susceptible to damage during cyclic loading. Overall, the EP porous NiTi alloy exhibited a higher compressive strength, enhanced compression recovery properties and cyclic stability compared to those reported in previous studies. This is because of the optimization of high-temperature homogenization via sintering at 1250 °C and enhancement effects of aging precipitation. This study provides a novel approach for developing porous EP NiTi alloys.

Multiple pulses of fluids involved in the formation of carbonatite-related REE deposits as revealed by fluorite

Formation of carbonatite-related REE deposits generally associated with hydrothermal fluids exsolved from carbonatite melts. Deciphering the nature and evolution of the fluids is critical for establishing ore-formation models, and was mostly benefited from multi-analytical investigation of specific minerals presenting in multi-generation veins. However, there is a risk that the minerals in specific-generation veins not always precipitated solely from the single-stage fluids particularly for a dynamic mineralizing system. In order to evaluate this potential risk, this study conducted a combined textural, in situ trace elemental and fluid inclusion investigation of fluorite from multiple generations of veins in the Muluozhai carbonatite-related REE deposit, SW China. The veins dominate the mineralization system of the deposit, and include four generations/stages: fenitization (Stage I), pre-REE (Stage II), early REE (Stage III) and late REE (Stage IV) stages in which the ore minerals are all dominated by bastnäsite. Fluorite grains are widely present in these generations of veins, but high-resolution CL imaging reveal that most of them display complex internal textures composed commonly of core, mantle and rim domains from center outward. These domains exhibit different CL-intensities that are well correlated with chemical compositions and even types of fluid inclusions they hosted. This study confirmed that the “core-mantle-rim” textures of fluorite are essentially responses to interaction of early grains (i.e., represented by cores) with multi-stage fluids through dissolution-reprecipitation processes. Trace elemental and fluid-inclusion microthermometric results show that the cores (also for mantles or rims) in fluorite from Stages I to III veins have comparable REE concentrations and patterns and homogenization temperatures of fluid inclusions, strongly suggesting that the core-mantle-rim fluorite grains in these veins are originally formed at Stage I, and were variably captured or metasomatized by fluids of Stage II or III during development of these generations of veins. Similar core-mantle-rim fluorite grains are also present in Stage IV veins, and thus are constrained to be also “xenocrysts” formed in a similar manner. They are surrounded or even locally disturbed by a number of euhedral and/or slightly oscillatory fluorite grains which are supposed to be formed from a different manner. On the basis of their close association with bastnäsite and relatively high homogenization temperatures of fluid inclusions they host, we proposed that these euhedral fluorite grains are products of Stage IV fluids.Clear understanding of the internal textures and paragenesis of fluorite allows us to propose a genetic model for the Muluozhai deposit that the REE mineralization in Stages III and IV involves likely different pulses of carbonatite-related REE-rich fluids, and REE deposition was possibly mainly triggered by incursions of external fluids (e.g., meteoric water). This study also highlights that the phenomenon regarding presences of early-stage “xenocrysts” in late-generation veins of carbonatite-related vein systems may be more common than previously thought, and thus investigation in a textural context is critical for deciphering ore genesis.

MICROSTRUCTURE AND PHASE CONTENT OF INCONEL 718 SUPERALLOY PRODUCED VIA SELECTIVE LASER MELTING PRO-CESS, HOT ISOSTATC PRESSING AND HEAT TREATMENT

Purpose. Study of microstructure and phase content of Inconel 718 nickel-chromium-iron superalloy obtained via selective laser melting with subsequent hot isostatic pressing (HIP) and standard heat treatment with high-temperature homogenization and two-steps long term ageing.&#x0D; Research methods. Microstructure analysis and phase content investigation was carried out with optical and scanning electronic metallography on optical and electronic microscope respectively.&#x0D; Results. Material structure of in-built specimens are investigated that is characterized by layer-by-layer fusing in the form of arcuate lines with a presence of epitaxial growth of columnar dendrites. Strengthening of alloy is achieved after heat treatment, basically, due to intermetallic γ″- phase (with Ni3Nb type) precipitation. With metallographic investigation showed that active segregation of niobium in interdendritic spaces, provided due high crystallization rate during selective laser melting and subsequent heat treatment, lead to forming orthorhombic d- phase in alloy structure with lamellar morphology. HIP application before standard for Inconel 718 heat treatment, promotes more homogeneous structure.&#x0D; Scientific novelty. New data’s was obtained for phase state of Inconel 718 alloy after HIP and heat treatment. Fine structure of Ni-Cr-Fe-superalloy obtained via selective laser melting was studied.&#x0D; Practical value. Obtained results expands possibilities for Inconel 718 alloy application and allow to determine perspectives of practical usage of selective laser melting process for aviation parts production.

Oxidation and internal nitridation behaviors of a Ni-based superalloy Rene 65 during high-temperature homogenization

Oxidation and internal nitridation behaviors of a Ni-based superalloy Rene 65 during high-temperature homogenization

Genesis of granular calcite in lacustrine fine-grained sedimentary rocks and its indication to volcanic-hydrothermal events: A case study of Permian Lucaogou Formation in Jimusar Sag, Junggar Basin, NW China

Granular calcite is an authigenic mineral in fine-grained sedimentary rocks. Core observation, thin section observation, cathodoluminescence analysis, fluid inclusion analysis, scanning electron microscope (SEM), and isotopic composition analysis were combined to clarify the genesis of granular calcite in the lacustrine fine-grained sedimentary rocks of the Permian Lucaogou Formation in the Jimusar Sag, Junggar Basin. It is found that the granular calcite is distributed with laminated characteristics in fine-grained sedimentary rocks in tuffite zones (or the transitional zone between tuffite and micritic dolomite). Granular calcite has obvious cathodoluminesence band, and it can be divided into three stages. Stage-I calcite, with non-luminesence, high content of Sr element, inclusions containing COS, and homogenization temperature higher than 170 °C, was directly formed from the volcanic-hydrothermal deposition. Stage-II calcite, with bright yellow luminescence, high contents of Fe, Mn and Mg, enrichment of light rare earth elements (LREEs), and high homogenization temperature, was formed by recrystallization of calcareous edges from exhalative hydrothermal deposition. Stage-III calcite, with dark orange luminescence band, high contents of Mg, P, V and other elements, no obvious fractionation among LREEs, and low homogenization temperature, was originated from diagenetic transformation during burial. The granular calcite appears regularly in the vertical direction and its formation temperature decreases from the center to the margin of particles, providing direct evidences for volcanic-hydrothermal events during the deposition of the Lucaogou Formation. The volcanic-hydrothermal event was conducive to the enrichment of organic matters in fine-grained sedimentary rocks of the Lucaogrou Formation, and positive to the development of high-quality source rocks. The volcanic-hydrothermal sediments might generate intergranular pores/fractures during the evolution, creating conditions for the self-generation and self-storage of shale oil.

Investigation of High Temperature Homogenization of a Single-Crystal Nickel-Based Superalloy of the Third Generation

Investigation of High Temperature Homogenization of a Single-Crystal Nickel-Based Superalloy of the Third Generation

Composition and evolution of ore-forming fluids in the Sansheng porphyry W-Mo deposit, Inner Mongolia, NE China: Evidence from LA-ICP-MS analysis of fluid inclusions

Unveiling the composition and evolution of ore-forming fluids in porphyry W-Mo mineralization systems is key to understanding their formation processes, but detailed quantitative studies are still limited. The Sansheng porphyry W-Mo deposit (17,285 t WO3 @ 0.569 % and 24,361 t Mo @ 0.226 %), located in southern Great Xing’an Range W belt, NE China, is characterized by quartz vein- and veinlet-disseminated-type W-Mo ore bodies mainly hosted in the cupolas of Early Cretaceous granitic intrusion. In this study, we provide an elaborate study that integrates detailed petrographic, laser Raman, microthermometric, and LA-ICP-MS analyses of fluid inclusions (FIs) to reconstruct the fluid evolution history of the Sansheng W-Mo mineralization system and to bridge the aforementioned knowledge gap. Four stages of hydrothermal veins are identified: stage 1 is the dominant stage of W mineralization, and characterized by the development of wolframite, quartz, K-feldspar, muscovite, and minor amounts of molybdenite; stage 2 is the main stage of Mo mineralization, and featured with the mineral assemblages of molybdenite, quartz, sericite together with minor amounts of pyrite; stage 3 involves Cu-Pb-Zn mineralization, and is characterized by the occurrence of polymetallic sulfides, quartz, and sericite; and stage 4 is dominated by barren carbonate-quartz veins. In wolframite and quartz, the FIs are classified as liquid-rich two-phase (L-type), vapor-rich two-phase (V-type), and pure vapor mono-phase FIs (PV-type) in types. Microthermometric results reveal decreasing homogenization temperatures in primary FIs from stages 1 to 4. Stage 1 fluids are characterized by high homogenization temperatures (320–420 ℃), moderate salinities (7.9–14.8 wt% NaCl equiv.), highly variable W contents (17–7251 ppm) and constant Mo contents (22–288 ppm). FIs in wolframite and coexisting quartz share similar homogenization temperatures and salinities, suggesting that they were formed concurrently. Stage 2 fluids have similar salinities (7.0–13.9 wt% NaCl equiv.) to stage 1 fluids but lower homogenization temperatures (250–340 ℃), and contain highly variable Mo contents (21–11176 ppm) and low W contents (5–23 ppm). Stage 3 fluids display moderate homogenization temperatures (220–300 ℃) and low salinities (3.1–10.1 wt% NaCl equiv.). The contents of W and Mo in stage 3 fluids decrease dramatically, marking the termination of W-Mo mineralization. Stage 4 fluids are characterized by moderate homogenization temperatures (200–270 ℃), low salinities (0.2–5.0 wt% NaCl equiv.), and the lowest contents of W (1–4 ppm) and Mo (8–16 ppm). All stage fluids contain high concentrations of B and Mn, and high ratios of Li/Na, K/Na, Rb/Na, Ba/Na, Pb/Na, and Zn/Na, similar to magmatic-hydrothermal fluids in composition and against typical basinal brines. In addition, they also have high Rb/Sr and low K/Rb ratios, which are equivalent to those of the Sansheng ore-bearing granite. In combination with the constant Cs/(Na + K) and Cs/Rb ratios of all stage FIs, we propose that the multistage hydrothermal fluids originated from a common source–the highly evolved and geochemically uniform Sansheng granitic magma, and that the derivation of ore-forming fluids was a continuous fluid exsolution process. Fluid boiling and fluid-rock interaction are collectively responsible for the deposition of wolframite and molybdenite, while the role of fluid cooling may be subordinate. The meteoric water began to enter the hydrothermal system in stage 3, and fluid cooling and dilution due to the fluid mixing process played a critical role in the deposition of Cu-Pb-Zn sulfides. Our findings highlight the significance of in-situ FI analyses in revealing the composition and evolution of multistage fluids in porphyry W-Mo deposits, which is critical for elucidating detailed ore-forming processes of intrusion-related W-Mo mineralization systems in NE China and globally.

Evidence of deep fluid activity in Jurassic tight sandstone reservoirs in the Northern Kuqa Depression

Understanding diagenetic fluid types and their effects on diagenesis is important to identify the main control factors of reservoir characteristics and predict reservoir sweet spots. Reservoir space destruction caused by strong cementation is notable in the Lower Jurassic Ahe Formation sandstones near the deep-rooted fault (Yiqikelike Fault) in the Kuqa depression. Different authigenic minerals and widely varying cementation contents indicate the complexity of diagenetic fluids. Therefore, we investigated strong cementation using petrographic and geochemical methods, including cathodoluminescence, scanning electron microscopy, laser ablation inductively coupled plasma mass spectrometry, and stable isotope analysis. The contents of authigenic quartz and calcite increased as they approached the deep-rooted fault, with maximum concentration of quartz and calcite of up to 8.73% and 8.92%, respectively. Abnormally high homogenization temperatures of the fluid inclusions were observed in the quartz overgrowth, one of which reached 156 °C. In calcite, the rare earth element Eu exhibited abnormal characteristics, and the carbon isotopes ranged from −8.00‰ to −2.00‰. Therefore, it is likely that deep fluids are involved in reservoir diagenesis near a deep-rooted fault. This study provides a good example of diagenetic evolution in deep sandstone reservoirs and the negative effects of the involvement of deep fluids in diagenetic processes.

Mineralization and genesis of the orogenic gold system in the Kalamaili area, East Junggar, Xinjiang, northwestern China

There are many lode gold deposits and occurrences in the Kalamaili area of the East Junggar, northwestern China. However, little is known about the specifics of ore geology and geochemistry of these gold deposits because of very limited exploration and research work in this region. Field geology, fluid inclusions, stable isotopes, trace elements in quartz, and hydrothermal zircon U-Pb dating are combined in this study to constrain the nature and source of ore fluids, the timing of mineralization, and the mechanism of gold precipitation in Kalamaili. The gold deposits are confined to a narrow zone between two regional NW- to NWW-trending shear zones and are structurally controlled by secondary, high-angle faults of the shears. The orebodies occur in the Middle Devonian and Lower Carboniferous, zeolite to lower greenschist facies clastic sedimentary and pyroclastic rocks. Gold mineralization occurs as auriferous quartz-sulfide ± tourmaline veins/veinlets and disseminated ores in the immediate altered wall rocks. The ore mineralogy is relatively simple and dominated by quartz with minor to trace amounts of sulfides (pyrite and arsenopyrite), sericite, calcite, and native gold. Quartz of various generations contains three types of fluid inclusions, including predominant H2O-CO2-NaCl inclusions and subordinate H2O-NaCl inclusions and CO2 ± CH4 ± N2 inclusions. The mineralizing fluid is uniformly characterized by a medium to high homogenization temperature (mostly 240−330 °C), low salinity (typically &amp;lt;6 wt% NaCl equivalent), reduced, and CO2-rich-H2O-NaCl ± CH4 fluid. The hydrogen and oxygen isotope data (δ18OH2O = +5.6‰ to +14.3‰, δDH2O = −99‰ to −62‰) indicate a metamorphic origin for the mineralizing fluid. The majority of sulfide δ34S values range between 0‰ and +10‰, indicative of a largely sedimentary rock reservoir of sulfur in the ore-forming fluids. Geochemically, the auriferous quartz is characterized by low concentrations of most trace elements including Ti, Al, Li, Ge, and Sb. Laser ablation−inductively coupled plasma−mass spectrometry U-Pb isotope dating of hydrothermal zircons from the auriferous quartz vein yielded a weighted mean 206Pb/238U age of ca. 313 Ma. Phase separation of ore fluids and fluid-rock interaction are suggested as key mechanisms for the gold precipitation. Integrated geological and geochemical evidence indicates that formation of the orogenic gold system in Kalamaili is related to the transition from compressional to transcurrent deformation during the Late Carboniferous. Target gold exploration in this region should focus on the northeast side of the Kalamaili fault zone, where there exist suitable structural and stratigraphic trap sites with high fluid flux and potential gold mineralization.

Heat denaturation enables multicolor X10-STED microscopy

Expansion microscopy (ExM) improves imaging quality by physically enlarging the biological specimens. In principle, combining a large expansion factor with optical super-resolution should provide extremely high imaging precision. However, large expansion factors imply that the expanded specimens are dim and are therefore poorly suited for optical super-resolution. To solve this problem, we present a protocol that ensures the expansion of the samples up to 10-fold, in a single expansion step, through high-temperature homogenization (X10ht). The resulting gels exhibit a higher fluorescence intensity than gels homogenized using enzymatic digestion (based on proteinase K). This enables the sample analysis by multicolor stimulated emission depletion (STED) microscopy, for a final resolution of 6–8 nm in neuronal cell cultures or isolated vesicles. X10ht also enables the expansion of 100–200 µm thick brain samples, up to 6-fold. The better epitope preservation also enables the use of nanobodies as labeling probes and the implementation of post-expansion signal amplification. We conclude that X10ht is a promising tool for nanoscale resolution in biological samples.

The effects of chemistry variations on hot cracking susceptibility of Haynes® 282® for aerospace applications

Hot cracking susceptibility of Haynes® 282® with varying amount of C (0.05–0.09 wt%), Mn (0.03–0.12 wt%), Si (0.03–0.16), B (0.005–0.006 wt%) and Zr (0–0.01) are investigated. Synergistic role of C and B is found on solidification and heat affected zone (HAZ) liquation cracking susceptibility. High amount of C and B promote formation of eutectic constituents during final stages of solidification and promote crack healing by backfilling effect. When C and B are added in low amount the crack healing does not occur due to the absence of eutectic consituents therefore cracking extent increases. Thermodynamics simulations indicate C and B tie up to MC carbides and M3B2 borides during solidification. Scanning Electron Microscopy and Nanoscale secondary ion mass spectrometry analysis reveal C and B to be present both in solid solution and in form of precipitates to Ti-Mo rich carbides and Mo rich borides, respectively. In HAZ, these phases promote liquation cracking where cracking extent correlates to the amount carbides and borides. Lower C and B is found to reduce the liquation cracking in the HAZ. Furthermore, a high temperature homogenization heat treatment at 1190 °C excarbates the cracking by dissolving the borides and releasing B to the grain boundaries.