High Homogenization Temperatures Research Articles

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.

Effect of heat treatment on microstructures and mechanical properties of Inconel 718 additively manufactured using gradient laser power

To achieve high-performance nickel-based superalloys by laser powder deposition for applications in the aviation industry, post-heat treatments are always indispensable. We prepared two typical as-deposited microstructures by constant laser power deposition (CLP) and gradient laser power deposition (GLP), respectively. A systematic research on the room-temperature microstructural evolution, hardness, tensile property and fracture morphology of Inconel 718 after three kinds of heat treatments is performed. The as-deposited microstructure and segregation ratio (SR) can significantly influence the microstructure evolution. The as-deposited GLP samples with fine discrete Laves phases and a low SR can achieve a relatively uniform element distribution and γ′′ and γ′ phase precipitation after standard solution treatment plus aging (STA), while CLP samples with coarse long-chain Laves phases and high SR require a high-temperature homogenization plus STA (HSTA) heat treatment to achieve the uniform element distribution. Differences in heat treatments have a greater impact on the fracture mechanism. With the transformation of heat treatments from direct aging, STA to HSTA, the fracture mode of both CLP and GLP samples transforms from a ductile transgranular fracture mode to a mixed mode of transgranular and intergranular fractures.

The Relationship between Fluid Evolution and Hydrocarbon Accumulation and Metallization in the Nanpanjiang-Youjiang Basin: Evidence from Calcite Petrography and Fluid Inclusions

In the process of diagenesis and burial of sedimentary basins, basin fluid activities participate in the process of hydrocarbon accumulation and metal mineralization. Understanding the evolution of basin fluid is of great significance in revealing the related hydrocarbon accumulation and mineralization. Paleo-reservoirs are closely associated with Carlin-type gold deposits in the Nanpanjiang-Youjiang Basin, South China. Calcite, the fluid activity product, is closely related to bitumen and gold-bearing pyrite. By integrating petrographic, cathode luminescence, and fluid inclusion analysis, as well as the relevant chronological results of predecessors, this paper attempts to establish the relationship between fluid evolution, hydrocarbon accumulation, and gold mineralization. Two types of calcite (black/gray and white) developed in the Banqi-Yata-Laizishan area, the Nanpanjiang-Youjiang Basin. Black/gray calcite is symbiotic with bitumen and features dark red colors in cathode luminescence. Many hydrocarbon inclusions developed along with fluid inclusion analysis at low homogenization temperatures (65.7~173.1 °C). Combining the previously reported U-Pb ages (~250–230 Ma) of this kind of calcite with some geochemistry data on the associated reservoir and gold deposit, this calcite records the consecutive hydrocarbon accumulation and Carlin-type gold mineralization from the Late Permian to the Late Triassic periods controlled by Indosinian tectonic movement. The white calcite featuring bright red in cathodoluminescence is symbiotic with gold-bearing pyrite and realgar, and the associated fluid inclusions have high homogenization temperatures (128.2~299.9 °C). Combined with regional tectonic background and isotopic chronology (~140–106 Ma), it seems to record the early Cretaceous Carlin-type gold mineralization controlled by the subduction of the paleo-Pacific plate in the late Yanshanian period.

The morphology and characteristics evolution of MC carbide during homogenization in hard-to-deform superalloy GH4975

Microstructure control of hard-to-deform nickel-base superalloy with high content of γ′ phase is a hot topic, while the characteristic of MC carbide is often ignored. In present work, the morphology and characteristic evolution of MC carbide in a typical hard-to-deform superalloy GH4975 during high temperature homogenization is investigated by multiple characterization methods. The effect of MC carbide characteristic on deformation coordinate of the alloy is also studied by Gleeble isothermal hot compression. The precise chemical formula of MC carbide in as-cast GH4975 alloy is determined by precise micro-chemical analysis to be (Ti0.474Nb0.361Mo0.029W0.129)C. Typical morphology of MC carbide in as-cast alloy is large irregular particle with sharp corners and the elastic modulus of carbide is much higher than that of matrix. The morphology and elastic modulus of MC carbide result in apparent crack during hot deformation. The weight fraction of MC carbide decreases by 1/3 after 1180 ℃− 50 h homogenization. Chemical composition of MC carbide changes during homogenization with rejection of W and Mo to make the phase more stable. The morphology of MC carbide tends to be round to lower Gibbs free energy and elastic modulus decreases at the same time. No crack is detected during hot compression in homogenized sample. The morphology and elastic modulus evolution of MC carbide during homogenization increase the deformation coordination of the alloy. Hence, enough attention should be paid on MC carbide in wrought superalloy in the investigation of microstructure control.

PROTECTIVE TECHNOLOGICAL COATING BASED ON ZrO2–BaO–B2O3–SiO2 SYSTEM FOR PROTECTION OF HEAT-RESISTANT NICKEL ALLOY WITH SINGLE-CRYSTAL STRUCTURE DURING HEAT TREATMENT

The purpose of this work was developing of protective technological coating for protection of heat-resistant nickel alloy with single-crystal structure ZHS30 during high-temperature homogenization. Based on characteristics of the alloy the synthesis of coatings was carried out in following directions: modification of known coatings in the system CaO–BaO–SiO2 by introducting refractory filler and organosilicon materials, research of two-layer coatings and synthesis of refractory frits in various silicate systems. The best properties of alloy ZHS30 are obtained using a coating based on a synthesized frit containing SiO2, B2O3, BaO, ZrO2. High efficiency of the protective action of the coating is ensured by the chemical composition of the frit which leads to the formation of structural groups [BO4] in the glass that participate in the formation of the glass lattice. Zirconium ions also participate in the construction of the structure and together with silicon and boron ions form a single boron-zirconium-silicon-oxygen framework of high degree of polymerization. The revealed liquation structure of the frit consists of two glass phases: the more easily low-melting matrix contains drop-like inhomogeneities distributed in it enriched of SiO2 which explains the steadiness and stability of the glass at operating temperatures.

Enhancing the comprehensive properties of as-cast Cu–Ni–Si alloys by continuous extrusion combined with subsequent thermomechanical treatment

Producing high-strength and high electrical conductivity Cu–Ni–Si alloys from as-cast state to thin strips is a challenging issue in the industry, as high-temperature homogenization, multi-step rolling, and aging processes are frequently employed and, any mistakes in each step can affect the quality of the product. In the present study, the comprehensive properties of an as-cast Cu–Ni–Si alloy were improved by a short process, i.e., continuous extrusion combined with rolling and aging processes, without homogenization treatment. The results indicated that both the mechanical and electrical properties of the alloy at the optimized route were dramatically enhanced. A final microstructure containing fine grain sizes, massive precipitates, and dislocations was obtained, thus contributing to high tensile strength (763 MPa), high electrical conductivity (49.6% IACS), and good ductility (5.8% fracture elongation). The strengthening mechanisms were then quantitively calculated. The results showed that the dislocation strengthening, grain boundary strengthening, and precipitation strengthening take 25.2%, 16%, and 51.2% of the total yield strength, respectively. It has also been found that there are two sizes of precipitates and both were identified to be δ1-Ni2Si. Although the volume fraction of the fine Ni2Si is small, it contributes to a large portion of the yield strength. Hence, there is great potential to control the precipitate size to enhance the strength of the Cu–Ni–Si alloy further for this combined technique.

Evaluation of the properties of dolomitization fluids and diagenetic alterations of mg/Ca ratios in carbonate rocks in the cambrian series-2 to miaolingian strata in Central Uplift Belt, Tarim Basin: Constraints from halogens, REEs and isotope geochemistry

The nature of the dolomitization fluids and the diagenetic alterations on carbonate Mg/Ca ratios in Cambrian series-2 to Miaolingian strata in Central Uplift Belt, Tarim Basin are interpreted on the basis of petrography, geochemistry (trace elements, halogens, REEs, O–C–Sr isotopes) and fluid inclusion microthermometry. Based on petrographic examination, two types of less stoichiometric dolomites: dolomicrites (DM), very fine-to fine-crystalline planar-e(s) dolomite (D1) formed at near-surface to shallow-burial settings, and two types of more stochiometric dolomites (fine-to medium-crystalline planar-e(s) dolomite (D2) and medium-to coarse-crystalline.nonplanar-a dolomite (D3)) formed at deep-burial setting are identified. Medium-to coarse-crystalline, nonplanar-a saddle dolomite cement (DC), and early-stage calcite cement (ESCAL) and later-stage calcite cement (LSCAL) are identified. The DM, D1, D2, and D3 samples display positive Cerium anomalies (δCe) and negative Europium anomalies (δEu), and the DC display positive δCe and positive δEu. They show micritic-bladed and blocky calcite-like REE patterns, suggesting their dolomitizing fluids inherited the seawater or seawater-like REE signatures of their precursor carbonate materials at the time of crystal growth. No correlations exist between δ13C, δ18O, 87Sr/86Sr, Mg/Ca, and Mn/Sr which were tools used to evaluate the diagenetic history of the carbonates, coupled with the high Mg/Ca ratios (0.64–0.85), Mn/Sr ratios, and more depleted δ18O, δ13C values of D2, D3, and DC. This suggests that the dolomites were altered by high-temperatures or their isotopic difference may be the result of equilibrium isotopic fractionation. The increasing trend in Cl/(Ca + Mg), I/(Ca + Mg), and Br/(Ca + Mg) ratios in the D2, D3, and DC with dolomite content >50 wt% can be explained by the presence of evaporite (salt) derived from seawater or sedimentary pore waters as fluid interaction with sedimentary materials in the studied strata. The comparable isotopic (δ18O, δ13C and 87Sr/86Sr) values between DM, D1, D2, D3, DC, and coeval Early Paleozoic seawater value, coupled with the relatively high homogenization temperature (Th) and salinity levels in D2, D3, and DC, indicates that their diagenetic fluids were derived from radiogenic 87Sr-enrich coeval seawater with hypersaline signatures in deep-burial settings. The dolomitization model shows that the precipitation of dolomicrites was by evaporative seepage-reflux dolomitization at near-surface burial settings. Evaporative seawater dolomitization supported by 87Sr/86Sr, δ13C values and calculated water oxygen isotope ratio was probably responsible for the D1 during shallow-burial, and D2 and D3 with irregular overgrowth rims were formed during deep-burial dolomitization. The average range of the Th values of DC is 148.2–193.4 °C; mostly overlapping with the estimated ambient temperature (65 °C–180 °C, at a depth >4000 m) for the studied strata, indicates that the growth of DC in fractures may have resulted from upward and laterally squeezed higher-temperature saline-enriched basinal fluids conveyed by geothermal convective-advective fluid flows or squeegee fluid flows at depth resulting in geothermal dolomitization.

Multistage fracturing history in the Paleocene lacustrine shale oil reservoirs of the Subei Basin, Eastern China

This study examines sealed fractures in core samples from the Paleocene organic-rich lacustrine shales of the Gaoyou Depression, Subei Basin, China, using a multi-pronged approach to elucidate the interplay between fracture propagation and fluid circulation in shaly successions. Based on petrography, geochemistry, and geochronology of fracture-filling minerals, four generations of vein emplacement (denoted Types A-D) were identified. These were attributed to successive episodes of burial diagenesis, tectonism, and uplift occurring at different phases of basin evolution. These vein generations were then inserted into the temporal-spatial framework derived from basin modeling, leading to a reconstruction of the fracture diagenesis history in the Funing shales. Two of the vein generations contain evidence for two phases of oil migration marked by two types of oil inclusions with different fluorescence.It has been shown that the studied lacustrine shales were deposited at ca. 60.2–58.0 Ma. The earliest vein generation, represented by antitaxial beef calcite veins sub-perpendicular to shale bedding, propagated in incompletely consolidated shales within a regional thrust regime related to the Wubao Movement. The vein nucleation during a short-lived burial following initial deposition was also evidenced by the presence of monoliquid inclusions in the veins and calcite LA-ICP-MS U–Pb age (57.7 ± 3.7 Ma). Tectonic compressive stress together with overpressures arising from horizontal and vertical disequilibrium compaction were interpreted as being responsible for this fracturing episode. The second vein generation is bedding-parallel, oil inclusion-rich stretching calcite veins with a crack-seal texture, formed concurrently with kerogen maturation and early oil generation at moderate burial depths. The vein crack-seal fills containing yellow fluorescing oil inclusions provide evidence for episodic oil expulsion in response to cyclic rises and drops in pore pressure during the oil window. Bedding-parallel beef calcite veins characterized by antitaxial growth represent the next vein generation, emplaced during the maximum burial period (ca. 41.9 ± 2.7 Ma). The vein fibers have tracked the horizontal displacement of the wall rocks, likely related to lateral shortening before or at the initiation of Late Eocene basin inversion. The first three vein generations were generated in a relative closed fluid system, with vein fill sourced locally. Host-rock carbonate components and/or earlier diagenetic carbonates were dissolved and then mobilized into these veins. By contrast, the last vein generation with blocky calcite and barite cementation is associated with input of externally derived hydrothermal fluids. The evidence comes from abnormally high fluid-inclusion homogenization temperature (Th) and salinity data, as well as the fact that Ba and sulfate were sourced from the underlying evaporite layers rather than local shales. We thus infer that cross-stratal faulting during the uplift related to the Sanduo Movement resulted in the opening of initial hydraulically closed fluid system. This episode of tectonically-driven hydrothermal circulation from deeper locations in the basin into the Funing shales led to the mixing of oil-bearing pore fluids with exotic basinal hot brines. This also accounts for the presence of abundant blue-green fluorescing oil inclusions and significantly elevated fluid salinity. Overall, this study emphasizes that during basin evolution, differences in tectonic settings and the diagenetic boundary conditions under which veins formed results in different fracturing mechanisms and associated fluid-flow regimes in shale sequences, with consequent effects on vein attributes and mineralization.

Characteristics of Source Rocks and Formation of Reservoir Bitumen in Yinchuan Graben, Ordos Basin, China

The Yinchuan Graben is an important potential exploration area that is located on the western margin of the Ordos Basin. Over 8000 m of Cenozoic strata have been formed since the Cretaceous. With an integrated approach of cores observation, logging analysis, and geochemical analysis, we analyzed the characteristics of the Cenozoic source rocks in the Yinchuan Graben and determined the formation and destruction of the fossil oil reservoirs. With type III kerogen, the TOC of the dark mudstone in the Qingshuiying Formation is up to 7.5%, and the Ro is 0.95–1.04%, indicating the source rocks have entered the mature stage but the hydrocarbon generation potential is insufficient. A quantity of reservoir bitumen and oil-bearing fluid inclusions (GOI = 1.67–4%) were found in the Qingshuiying Formation sandstone in Well YQ-1, which indicates a fossil oil reservoir had existed. The fossil oil reservoir and reservoir bitumen were generated by the unexplored pre-Cenozoic strata in the Yinchuan Graben. The reservoir bitumen has high maturity and is associated with many fluid inclusions with a high homogenization temperature or CO2. This indicates that the bitumen was formed by the pyrolysis of the oil which was caused by the hot fluid migrating along with the deep fault belts.

Multi-Phases Fluid Activity Characteristics of Longmaxi Formation and Its Impact on Resistivity in the Changning Area, Southern Sichuan Basin, Southwest China

Wells with low gas content and low resistivity in the Changning area, southern Sichuan Basin were selected for this study. The burial-thermal history was reconstructed and the characteristics of multi-phase fluid activity were clarified using microscopic observation and testing of fluid inclusions in the Longmaxi shale fracture veins. Compared with wells with a high gas content and high resistivity, the influence of fluid activity on resistivity was analyzed. The results showed that the thermal evolution of the bituminous inclusions trapped in the veins has reached the stage of carbonaceous-metamorphic bitumen, and the organic matter is fully cracked for gas generation, with some organic matter exhibiting the phenomenon of “graphitization.” The synchronous fluid with bitumen was existed due to shallow burial with a middle-low maturity stage of about 280 and 292 Ma. Two phases of fluids existed in the deep burial stage, thus maturing for about 103 Ma, and the uplift stage at about 28 and 32 Ma, with high homogenization temperatures (Th) (varying from 185 to 195°C and 165–180°C). The corresponding pressure coefficients varied between 1.67 and 2.09, 1.56 and 1.92 in a moderate-strong high-pressure state. The last two phases of fluid formation in the late uplift stage for about 4 to 19 Ma and 6 to 10 Ma were characterized by low salinity at medium-low Th (varied from 140 to 155°C and 120–135°C), with pressures of 57.47–74.50 MPa and 51.44–59.41 MPa (pressure coefficients of 1.09–1.41 and 1.18–1.37), in an atmospheric-weak overpressure state. In the initial uplift stage after deep burial, the fluid closure in the Changning area was good. In contrast, the wells are filled with low gas content because of the strong tectonic forces causing the shale gas to be released and the multi-phase fluid activity that happens during the late uplift stage. New evidence indicates that the emergence of low resistance in the localized Changning area is not only related to the high degree of evolution of organic matter but is also affected by the multi-phase fluid modification in the late uplift stage.

Strain localization at longitudinal weld seams during plastic deformation of Al–Mg–Si–Mn–Cr extrusions: The role of microstructure

The current work was motivated by the increasing use of hollow aluminum extruded profiles for automotive applications and the need for a better understanding of the mechanical response of extrusion seam welds. Two Al–Mg–Si alloys were studied, one without Mn and one with 0.5 wt%Mn and 0.15 wt%Cr. A high temperature homogenization was applied, resulting in a high density of α-Al(Fe,Mn)Si dispersoids in the Mn containing alloy, and an essentially dispersoid free microstructure in the other. The alloys were extruded through a simple porthole die (with two ports) to produce a strip with a centerline weld seam. The Mn free extrudate had a recrystallized grain structure whereas the Mn and Cr containing material was unrecrystallised. There were significant spatial variations of microstructure between the weld seam and surrounding regions, in particular the crystallographic texture. Tensile tests were conducted with the loading direction perpendicular to the weld seam using digital image correlation (DIC) to characterize the local strain distribution. Strain localization and final fracture occurred at weld seam for the unrecrystallized material whereas these occurred away from the weld line in the recrystallized case. The role of local crystallographic texture was examined through polycrystal plasticity simulations using the visco-plastic self consistent code (VPSC). These simulations indicated that the weld seam region was mechanically stronger than the surrounding region for the recrystallized alloy and correspondingly weaker for the unrecrystallized case, thereby rationalizing the experimental results of strain localization and final fracture location.

A study of iron carbonates and clay minerals for understanding the origin of marine ooidal ironstone deposits

A detailed study of cement and matrix of ooidal ironstones of the Bakchar deposit (Western Siberia) was carried out to assess the factors influencing ore-forming processes. This research focusses on a debated issue about iron sources for Phanerozoic ooidal ironstone. Siderite, the main cementing mineral in the ironstones, is of two varieties that differ in morphology, chemical and isotopic composition, and types of fluid inclusions. The first variety of siderite occurs either as veinlet or as anhedral cement, consisting of isotopically light carbon and oxygen (δ13C from −39.5 to −29.7‰ and δ18O from −15.2 to −5.1‰). Fluid inclusions show a relatively high homogenization temperature (170–320 °C) and methane in the gas phase, corresponding to methane-bearing hydrothermal fluids. The second variety of siderite occurs as aggregates of small crystals in the ironstone matrix and is relatively enriched in heavier stable carbon and oxygen isotopes (δ13C from −28.1 to −12.2‰ and δ18O from −28.4 to −2.1‰), suggesting its formation on the seafloor under the combined influence of methane flux and seawater. The zone of the ooidal ironstone most proximal to the most intense ore-mineralization, an area of intense diffusion of metals and methane through marine sediments, is marked by the first variety of siderite, with rare authigenic minerals, a low clay content (kaolinite, chlorite, nontronite) and a high Fe content of the smectites. The authigenic mineral associations reflect the transition from methanic (sulfate-methane transition zone) to ferruginous (iron reduction zone) through sulfidic environment. The intermediate zone is dominated by montmorillonite-illite-saponite-nontronite and the second variety of siderite. The distal zone of the ore deposit is relatively unaltered, and is marked by illite-montmorillonite (illite-smectite), with rare second variety of siderite. The ratio of 1 M phyllosilicates (kaolinite) to the main swelling 2 M phyllosilicates in the clay fraction (K/M mineral index) decreases from the proximal zone of the intense iron-mineralization to the distal zone. The trend of clay mineral changes reflects the decreasing alteration of sediment matrix away from the main iron-rich and/or carbonate-bearing fluid influx. This study shows the expected lateral and vertical variation in authigenic minerals associated with marine Phanerozoic ironstone deposits, related to variable flux of metal- and methane-bearing fluids.

Fluid evolution characteristics and ore genesis in the Jinqu Au deposit, Qinling Orogen, China: Implications for ore genesis

The Jinqu Au deposit is located in the central Xiaoqinling gold field along the southern margin of the North China Craton. Ore-bearing auriferous quartz veins in the deposit are controlled by E–W trending structures within amphibolite facies metamorphic rocks of the Archean Taihua Group. The ore-forming process in this deposit can be divided into four stages represented by feldspar-quartz, pyrite-quartz, polymetallic sulfide-quartz, and carbonate-quartz veins and veinlets. Here we present fluid inclusion and isotopic data of the Jinqu Au deposit. Four types of fluid inclusions in quartz and calcite are identified, including carbonic-aqueousinclusions (type-1), aqueousinclusions (type-2), solid-bearinginclusions (type-3) and pure carbonic inclusions (type-4) varieties, based on petrography and laser Raman spectroscopy. Quartz in stage I contains type-1 fluid inclusions (FIs) which homogenized to aqueous or carbonic phase at temperature 361 to 406 ℃ and 385 to 400 ℃ respectively, and have salinities of 10.3 to 17.9 wt% NaCl equiv. Type-2 FIs show homogenization temperatures of 347 to 410 ℃ into the liquid phase, with high salinities of 11.6 to 18.6 wt% NaCl equiv. Quartz in stage II is the major host of type-1 FIs, with minor type-4 FIs, the former showing homogenization at temperatures of 305 to 390 ℃ into the carbonic phase and 280 to 410 ℃ into the aqueous phase, with variable salinities of 4.5 to 19.8 wt% NaCl equiv. The stage III quartz contains all the four types of FIs (homogenizing to carbonic or aqueous phase at temperature 309 to 360 ℃ and 295 to 400 ℃, with salinities of 6.6 to 19.9 wt% NaCl equiv for type-1, and homogenizing to liquid at temperature 308 to 326 ℃ with salinities of 12.5 to 13.2 wt% for type-2 Fls). In stage IV, type-2 FIs are the major type in quartz and calcite with total homogenization temperatures of 213 to 280 ℃ into the liquid phase and variable salinities of 5.3 to 18.6 wt% NaCl equiv. Our data show that the ore-forming fluids of the Jinqu Au deposit are generally characterized by moderate to high homogenization temperatures and variable salinities, belonging to the CO2-H2O-NaCl ± CH4 system. Based on fluid inclusion data, we infer that fluid immiscibility occurred in stages II and III, and the estimated trapping pressures for stages II and III fluids are between 81 and 275 MPa.The CHO isotopic values of fluids (δ18Owater = 1.2 to 6.4 ‰; δDV-SMOW = − 68.5 to − 56.0 ‰; δ13CCO2 = − 12.4 to − 3.4 ‰) in stage I to IV and δ13CV-PDB values for calcite (δ13CV-PDB = − 7.6 to − 4.3 ‰) in stage IV suggest that the ore-forming fluids were composed of a mixture of metamorphic water and mantle-derived fluids with minor involvement of meteoric water. Fluid inclusions in pyrite of stage II and III yield 3He/4He ratios of 0.88 to 1.39 Ra, and considerable 40Ar/36Ar ratios range from 2287.6 to 5669.9, suggesting the mixing of mantle and crustal components. The δ34SV-CDT values of sulfide samples in stages II and III range from − 5.8 to 4.5 ‰ (except for a pyrite grain within calcite that shows − 28.5 ‰). The values of 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb of pyrite samples in stages II and III are from 16.919 to 17.321, 15.340 to 15.539, and 37.303 to 37.971 respectively. Our data suggest that the Taihua Group was possibly a major source for the ore-forming metals of the Jinqu Au deposit. Integrating the data from ore geology, fluid inclusions, isotope geochemistry and regional setting, we propose that the Jinqu Au deposit is an orogenic-type deposit which formed within the continental collision setting of the North China and Yangtze Cratons.

Oxidizing fluids associated with detachment hosted hydrothermal systems: Example from the Suye hydrothermal field on the ultraslow-spreading Southwest Indian Ridge

The redox state of hydrothermal fluids on mid-ocean ridges, which is indirectly affected by the depth of hydrothermal circulation and crustal permeability, plays an important role on the diversity of hydrothermal precipitates and associated ecosystems. Primary hydrothermal fluids that circulate along detachment faults are generally reducing as a result of the serpentinization of ultramafic rocks, while significant seawater infiltration may shift the redox state from reducing to oxidizing. However, the depth of penetration of oxidizing fluids into detachment related systems remain unclear, largely because current observations are based primarily on hydrothermal products that precipitated at the seafloor. Here, we report the first observations of oxidizing mineral assemblages in stockwork samples from the Suye hydrothermal field on the ultraslow spreading Southwest Indian Ridge. This field is hosted by mafic lithologies, while the low As, high Ni and Co contents, and high Au/As, Ag/As, and Ni/As ratios in pyrite from the stockwork samples indicate that the fluids reacted with both mafic and ultramafic rocks in the subseafloor. The high δ34S values (average of 9.8‰) indicate a high proportion (up to 50%) of seawater derived reduced sulfur involved in the stockwork zone formation. The high homogenization temperatures (∼320 °C) and salinity (∼12 wt.% NaCl) of fluid inclusions indicate that the stockwork zone of Suye was formed by a fluid that underwent phase separation deeper in the system that was subsequently diluted by 4–5 times subsurface seawater. The deep penetration of seawater is facilitated by the unique tectonic setting of the Suye hydrothermal field, which occurs between the two stage detachment faults that creates high permeability. Our findings demonstrate that hydrothermal fluid associated with detachment faults could be oxidized below the subsurface stockwork zone, and that deep-rooted detachment faults at ultraslow-spreading ridges can sustain both reducing and oxidizing hydrothermal systems in the same fault system. These results call for a reevaluation of the fate of base metal in ultramafic hosted hydrothermal fields.

Effect of Si Level on the Evolution of Zr‐Bearing Dispersoids and the Related Hot Deformation and Recrystallization Behaviors in Al–Si–Mg 6xxx Alloys

The precipitation behavior of Zr‐bearing dispersoids is investigated in Al–Si–Mg 6xxx alloys with different Si levels (0.4, 0.7, and 1.0 wt%) at three homogenization temperatures (450, 500, and 550 °C). The hot deformation behavior is studied using uniaxial compression tests at different Zener–Hollomon parameters. The microstructure evolution during hot deformation and postdeformation annealing is evaluated using the electron backscatter diffraction technique. The results show a significant influence of the Si level and homogenization temperature on the precipitation of two types of Zr‐bearing dispersoids. Si promotes the precipitation of both spherical L12–Al3Zr and elongated DO22–(Al,Si)3(Zr,Ti) dispersoids during low‐temperature homogenization. However, it accelerates the transformation of Zr dispersoids from L12 to DO22 at high homogenization temperature. The flow stress is more influenced by the solid solution level and hot deformation parameters rather than by the dispersoid distribution. The fine dense L12–Al3Zr dispersoids provide higher recrystallization resistance during postdeformation annealing compared with the large elongated DO22–(Al,Si)3(Zr,Ti) dispersoids. Owing to the uniform distribution of dispersoids and limited dispersoid‐free zones, the high Si alloy (1.0%) exhibits best recrystallization resistance among the three alloys studied.

Термодинамічний аналіз фазового складу протекторних сплавів на основі алюмінію

Literature review on magnesium, zinc and aluminum-based sacrificial anode alloys chemical and phase compositions have been performed. Technological phase diagrams of aluminum-based sacrificial anode alloys with different content of harmful additives, such as iron, silicon and copper, have been calculated and constructed. It is determined that the harmful effect of iron is in faster dissolution of the anode due to large inclusions of iron intermetallic. This iron negative effect can be eliminated in several ways: a) maximization of the melt cooling rate, which will lead to significant grinding of the intermetallics and thus reduce their negative impact; b) high-temperature homogenization of the alloy with subsequent rapid cooling, which will reduce the size of the iron intermetallic inclusions; c) doping the alloy with additional manganese to bind iron in ternary compound, which has a different shape and size than the binary intermetallic and has less negative effect on the sacrificial anode alloy. To eliminate the negative effects of silicon, the alloy has to be additionally doped with magnesium in an amount that will ensure the silicon complete binding. In this case, the phase composition of the alloy will correspond the AP4 alloy (% wt.%: (4.0-6.0) Zn), (0.5-1.0) Mg, (0.05-1.00) Sn , ˂ 0.10 Si, ˂ 0.10 Fe, ˂ 0.01 Cu). Long-term heat treatment of the alloy at a temperature of 120 ° C is proposed to reduce the copper harmful effect on the aluminum-based sacrificial anode alloys. Almost all copper can pass from the solid aluminum solution into the Al2Cu compound during this processing. Keywords: sacrificial anode alloys, aluminum alloys, impurities, technological phase diagrams.

Gradient-structured high-entropy alloy with improved combination of strength and hydrogen embrittlement resistance

High-strength materials usually exhibit poor hydrogen embrittlement resistance, and thus, there are demands for materials with high strength and good ductility under hydrogen. Here, gradient structures containing surface nanotwins are introduced in a CrMnFeCoNi high-entropy alloy by surface mechanical attrition treatment, and hydrogen embrittlement resistance is compared with coarse- and nano-structured alloys produced by high-temperature homogenization and high-pressure torsion, respectively. The coarse-grained alloy shows high ductility, but its yield stress is low. The nanostructured alloy shows ultrahigh yield stress, but with poor hydrogen embrittlement resistance. The gradient-structured alloys have both high yield stress (500–700 MPa) and good ductility (15–33%) under hydrogen.

Characteristics and Formation Mechanism of the Lower Paleozoic Dolomite Reservoirs in the Dongying Depression, Bohai Bay Basin

The Lower Paleozoic carbonate strata experience multi-stage tectonic activity and post-depositional volcanic activity in the Dongying Depression, Bohai Bay basin. These tectonic and magmatic activities have caused the reservoir to undergo severe diagenesis, resulting in strong reservoir heterogeneity. This study aims to identify the characteristics of dolomite, various reservoir spaces’ characteristics, the origin of different types of dolomite, and the porosity evolution. According to crystal size and morphology, dolomites can be divided into three kinds of matrix dolomites and four kinds of dolomite cements. The petrology and geochemistry of the dolomite suggests that matrix dolomite is formed from seawater. The medium-to-coarse-crystalline dolomite cement (D3) has a higher 87Sr/86Sr ratio (0.7119 to 0.7129) and a higher homogenization temperature (>125 °C), suggesting that the fluid for the precipitation of D3 is a mixed fluid formed by hydrothermal fluid eroding the 87Sr-rich feldspar sandstone. The strikingly negative δ18O values (−23.7 to −25.7‰ VPDB) of saddle dolomite (D4) indicate that D4 precipitated from hydrothermal fluids and the Mg2+ source may be due to dissolution of the host dolomite that formed in the evaporation environment. The reservoir spaces of the target strata in the study area mainly include fractures, dissolution vugs, intercrystalline pores, and moldic pores. Dissolution is the basis for forming high-quality dolomite reservoirs. The faults and fractures provided favorable conditions for dissolution. Hydrothermal fluid and organic acid were the main dissolution fluids for the dolomite reservoir, which were beneficial to the development of secondary pores. In the study area, organic acid dissolution was shown to contribute more than hydrothermal dissolution in the study area.

Refinement mechanism of cerium addition on solidification structure and sigma phase of super austenitic stainless steel S32654

• Ce addition could modify MgO and MnS into Ce 2 O 3 and Ce 2 O 2 S in S32654. • Ce addition leads to noticeable refinement of both dendrite structure and σ phase. • Effective Ce-bearing inclusions could serve as nucleation cores of γ and σ phase. • Solute Ce markedly enhances undercooling degree, further refining dendrite structure. • Solute Ce promotes σ phase nucleation, while dendrite refinement limits its growth. The influence of Ce addition on the solidification structure and σ phase of super austenitic stainless steel S32654 was systematically investigated via microstructural characterization and thermodynamic calculation. The results indicate that a small addition of Ce could modify MgO and MnS into Ce-bearing inclusions Ce 2 O 3 and Ce 2 O 2 S. Ce addition led to noticeable refinement of both the dendrite structure and σ phase. The refinement mechanism could be attributed to the combined actions of effective Ce-bearing inclusions and solute Ce. Effective Ce-bearing inclusions could serve as heterogeneous nucleation cores of austenite as well as σ phase, which provided a favorable prerequisite for their refinement. Solute Ce significantly enhanced the undercooling degree of the system, further promoting dendrite structure refinement. Meanwhile, solute Ce improved the eutectic precipitation conditions of σ phase and further promoted its nucleation, while the dendrite refinement limited its growth space. Finally, more fine and dispersed σ phase particles formed in S32654 with Ce addition. The refinement of dendrite structure and σ phase will reduce the temperature and time required for high-temperature homogenization, which is beneficial to the hot working of this steel.