Precipitation Of Phase Research Articles

Electropulsing rapidly refined the microstructure and enhanced the strength and plasticity of Cu-3.5Ti alloy

Recrystallization annealing is a necessary process for refining the grain of processed metallic materials and eliminating work hardening. However, it can cause a large amount of precipitation and coarsening of the second phase in supersaturated solid solution alloys, which is detrimental to the subsequent processing and aging processes aimed at controlling the precipitation phase. This article compared the effects of electropulsing (EPT) and conventional heat treatment (CHT) processes on the microstructure and mechanical properties of cold-rolled Cu-3.5Ti alloy. The results indicated that compared with CHT, EPT achieved full recrystallization of the alloy at a lower temperature (650 °C, 100 °C lower than CHT) and in a shorter time (10 s, 1/360 of CHT), and effectively inhibited the precipitation of β-Cu4Ti phase, resulting in a fine and uniform supersaturated solid solution. This process significantly improved both the strength and plasticity of the alloy. The yield strength, tensile strength and elongation to failure of the EPT-650 °C/10 s sample were 570 MPa, 598 MPa and 21.2 %, respectively, which were 27.8 %, 25.9 % and 19.1 % higher than those of the CHT-750 °C/1 h sample. EPT significantly increased the recrystallization nucleation rate of the alloy, while its rapid heating method inhibited the precipitation of β-Cu4Ti phase, ensuring the recrystallization process was not affected by the precipitated phase, which was the main reason for rapid recrystallization and grain refinement of Cu-3.5Ti alloy by EPT at lower temperatures and shorter time.

Precipitation suppression of refractory high-entropy alloys at intermediate temperature via adding oxygen

Due to the excellent mechanical properties, TiZrNb-based refractory high entropy alloys (RHEAs) show great potential application prospects in aviation, aircraft and petrochemical. However, the RHEAs are usually thermally metastable and brittle phases can be precipitated in intermediate temperature (such as 500–700℃), which severely limit the preparation of large-sized RHEAs ingots in industrial production. In this paper, we propose an alloy optimization strategy to suppress the precipitation of TiZrNb-based RHEAs by adding interstitial atomic oxygen (O). The results show that the precipitation temperature region of brittle phases can be reduced from 500°C∼650°C to 550°C∼600°C after adding oxygen, and the temperature region is reduced by more than 66 %. Moreover, the growth rate of precipitated phase decrease from 4.1 × 10−23 m3/s to 1.9 × 10−24 m3/s after adding oxygen, which is reduced by more than ten times. The analysis shows that adding oxygen inhibits the diffusion rate of Zr at intermediate temperature, thus delaying the formation of Zr-rich phase. Based on this, TiZrNb-based RHEAs with oxygen can well keep the outstanding ductility even after annealing at intermediate temperature for 4 hours, while the TiZrNb-based RHEAs without oxygen show ∼50 % ductility loss after the same annealing treatment. Our results not only provide new insights into the phase stability and mechanical stability of RHEAs, but also provide a new strategy for improving the phase stability of large-size ingots for engineering applications.

Research on microstructure and properties enhancement of TiN/GH5188 Co-superalloy composite fabricated by laser powder bed fusion

Improving mechanical properties effectively in Laser Powder Bed Fusion (LPBF) is a substantial challenge. Utilizing metal matrix composites with customizable TiN nanoparticle proportions presents an efficient strategy for fabricating high-strength LPBF parts. This study employed LPBF to fabricate TiN/GH5188 Co-based superalloy composites with alternative TiN nanoparticle contents (0, 0.5, 1, and 1.5 wt%). The effect of nano-TiN particles on the microstructure, texture evolution, and mechanical properties of TiN/GH5188 composites was investigated. Notably, the presence of nano-TiN acts as a reinforcing particle, facilitating the precipitation of the BCC strengthening phase, resulting in substantial strength enhancement. As the TiN content increases, the yield strength and microhardness consistently rise. At a 1.5 wt% TiN addition, a significant enhancement is observed, with yield strength rising by 22.0 % and microhardness increasing by 16.9 %. Although the aggregation of TiN precipitates into larger particles reduces ductility, the appropriate addition of TiN can effectively mitigate the microstructural anisotropy and induce a transition in the texture toward a non-preferred orientation, while maintaining high strength and ductility. A TiN/GH5188 composite containing 1 wt% TiN exhibits a yield strength and tensile strength of 822.4 MPa and 1131.8 MPa, respectively, accompanied by a microhardness of 334.3 HV. The elongation remains at 29.3 %, while exhibiting a non-preferred orientation (111) texture. Compared to GH5188, the yield strength, tensile strength and microhardness are increased by 17.6 %, 7.2 % and 12.1 %, respectively. This study demonstrates the significance of LPBF in producing high-performance TiN/GH5188 Co-superalloy composites and elucidates the potential mechanisms of TiN in improving microstructure and enhancing properties.

Performance evaluation of GH3536/GH4169 functionally graded materials with linear gradient changes fabricated through direct energy deposition

This study employs the direct energy deposition method to fabricate functionally graded materials (FGMs) using GH3536 and GH4169 alloys. The approach achieves a seamless linear gradient transition in the FGMs, progressing from GH3536 alloy to GH4169 alloy. Additionally, the impact of a solid solution twin-aging process on the properties of the FGMs was investigated. The findings reveal that variations in the powder content of GH3536/GH4169 alloy exhibit minimal impact on the microstructure of the deposited FGMs, with columnar crystals predominantly growing along the <001> direction. The direct energy deposition process induces an exceptionally high temperature gradient and cooling rate, preventing the timely precipitation of the second strengthening phase (γ", γ', δ), as well as M6C and M23C6 in the FGMs. Furthermore, the formation of the Laves phase (Ni2Nb, Cr2Mo) diminishes the overall performance of the FGMs. In correspondence with the linear variation of GH3536/GH4169 alloy powder content, the hardness of each layer within the deposited FGMs exhibits an initial increase followed by a subsequent decrease. Following the solution aging treatment, complete dissolution of the Laves phase and δ phase occurs, leading to the formation of a secondary chain phase (M23C6) along the grain boundaries. Simultaneously, needle and granular δ phases disperse within the grain structure, contributing to enhanced performance in the FGMs and ensuring uniform hardness throughout.

Aluminum doped non-stoichiometric titanium dioxide as a negative electrode material for lithium-ion battery: In-operando XRD analysis

Lithium-ion batteries (LIB) with titanium dioxide as anode material emerged as one of the most energy-storage systems. In this study, we investigate aluminum-doped non-stoichiometric titanium dioxide synthesized using sol-gel method and subsequent reduction treatment. Different analysis techniques, such as X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) tests are conducted for the analysis of material and performance of the battery. The XRD results affirmed that the sample consisted of pure titanium-dioxide phases with no other precipitated phases, such as aluminum oxide (α-Al2O3 or γ-Al2O3). XPS analysis evident that aluminum was successfully incorporated into the titanium-dioxide lattice and the presence of Ti3+ and oxygen vacancy signals confirmed its non-stoichiometric nature. TEM images implies that doping and its extent did not significantly affect the size and morphology of the nanoscale particles. The selected area electron diffraction shows that the sample consisted of a mixture of the anatase and rutile phases. The best-performing electrode was found to be the one composed of 1 % aluminum-doped non-stoichiometric titanium dioxide. After 200 charge-discharge cycles, the battery maintained a capacity of 195 mAh/g, retaining 97.5 % of its reversible capacity. Cyclic stability test under high current condition shows that the capacity remained at 157 mAh/g without any noticeable decay after 750 charge-discharge cycles at a 1 C rate. This material exhibited the lowest impedance and the highest lithium-ion diffusion rate. Additionally, in situ synchrotron-based XRD indicates coexistence of three phases such as a new reversible intermediate phase LiTiO2, a partially irreversible intermediate phase Li0.55TiO2, and the anatase phase. The analysis results indicated that the peak intensities and angular shifts were associated with the phase changes that occurred during charge and discharge of the electrochemical processes. The interaction mechanism study between lithium ions and the lattice of mixed phase (anatase, rutile) identified the occurrence of non-uniform stress resulting from lithium-ion insertion in the rutile phase, in addition to the irreversible reactions in both the rutile and anatase phases. Through the synergistic effect of heteroatom doping and oxygen vacancy treatment, the conductivity of titanium dioxide is enhanced, leading to improved performance in capacity, impedance, cycle life, and rate as an anode material in LIBs.

Design of a Thermally Stable Heat-Resistant (Al2O3+Al3Ti)/Al Composite with Excellent High-Temperature Mechanical Properties: Multimechanism Synergistic Strengthening Strategy.

The effectiveness of the room-temperature strengthening strategy for aluminum (Al) is compromised at increased temperatures due to grain and precipitate phase coarsening. Overcoming the heightened activity of grain boundaries and dislocations poses a significant challenge in enhancing the high-temperature strength through traditional precipitation strengthening. This study presents novel strengthening strategies that integrate intergranular reinforcements, intragranular reinforcements, refined grain, and stacking faults within an (Al2O3+Al3Ti)/Al composite prepared using sol-gel and powder metallurgy technology. Excellent high-temperature tensile properties are achieved; also, a remarkable fatigue performance at increased temperatures that surpasses those of other existing Al alloys and composites is revealed. These superior characteristics can be attributed to its exceptionally stable microstructure and the synergistic strengthening mechanisms mentioned above. This work offers new insights into designing and fabricating thermally stable Al matrix composites for high-temperature applications.

Hot Crack Formation Mechanism and Inhibition of a Novel Cobalt-Based Alloy Coating during Laser Cladding.

Laser cladding provides advanced surface treatment capabilities for enhancing the properties of components. However, its effectiveness is often challenged by the formation of hot cracks during the cladding process. This study focuses on the formation mechanism and inhibition of hot cracks in a novel cobalt-based alloy (K688) coating applied to 304LN stainless steel via laser cladding. The results indicate that hot crack formation is influenced by liquid film stability, the stress concentration, and precipitation phases. Most hot cracks were found at 25°-45° high-angle grain boundaries (HAGBs) due to the high energy of these grain boundaries, which stabilize the liquid film. A flat-top beam, compared to a Gaussian beam, creates a melt pool with a lower temperature gradient and more mitigatory fluid flow, reducing thermal stresses within the coating and the fraction of crack-sensitive, high-angle grain boundaries (S-HAGBs). Finally, crack formation was significantly inhibited by utilizing a flat-top laser beam to optimize the process parameters. These findings provide a technical foundation for achieving high-quality laser cladding of dissimilar materials, offering insights into optimizing process parameters to prevent hot crack formation.

Study on precipitation in (CoCrFeMnNi)90Al6Ti4 high entropy alloy

(CoCrFeMnNi)90Al6Ti4 high entropy alloy (HEA) was prepared by adding Al and Ti elements into CoCrFeMnNi HEA. The alloy underwent processes including copper mold suction casting, 1473 K homogenization, 30 % cold rolling + 1273 K annealing + 1073 K aging, and water quenching and heating treatment. Microstructure and phase composition of both as-cast and heat-treated (CoCrFeMnNi)90Al6Ti4 HEA were studied using metallographic microscope, scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD), and transmission electron microscope (TEM). The effect of heat treatment processes on the precipitation of second phases in (CoCrFeMnNi)90Al6Ti4 HEA was investigated, and mechanical properties of as-cast and heat-treated (CoCrFeMnNi)90Al6Ti4 HEA were studied via hardness tests. The results show that in as-cast (CoCrFeMnNi)90Al6Ti4 HEA, the second phase precipitated is primarily L21 structured AlTiNi2 phase. After homogenization, cold rolling, annealing, and aging processes, both the quantity and size of the second phase increase, with a small amount of nanoscale L12 phase appearing after aging treatment. With the progression of heat treatment, the hardness of (CoCrFeMnNi)90Al6Ti4 HEA increases, and mechanical properties are improved.

Quantifying the beta phase precipitation at low annealing temperatures and stress corrosion cracking behavior in Al–Mg alloys

Quantifying the beta phase precipitation at low annealing temperatures and stress corrosion cracking behavior in Al–Mg alloys

The influence of zirconium addition on microstructure evolution, precipitation behavior, and properties of Cu–Ni–Ti alloy

This study systematically investigated the effects of a small amount of Zr addition on the microstructure evolution, mechanical, and electrical properties of Cu–Ni–Ti alloy, specifically focusing on Cu–3Ni–1Ti - (0.3Zr). The results indicate that adding an appropriate amount of Zr significantly enhances the mechanical properties and over-aging resistance of the Cu–Ni–Ti alloy, with only a slight decrease in conductivity. After aging at 500 °C for 2 h, Cu–3Ni–1Ti-0.3Zr exhibits an ultimate tensile strength of 673 MPa and a conductivity of 53 % IACS. Even after extending the aging time to 10 h, the tensile strength and conductivity remain high at 646 MPa and 61 % IACS, respectively. Microscopic analysis reveals that the addition of Zr promotes the formation of fine Ni3Ti phase during solidification and solution treatment, improving the deformation resistance and enhances its yield strength of the alloy in the cold-rolled state. Additionally, it hinders the migration of grain boundaries，suppressing the recovery and recrystallization processes, thus maintaining high mechanical properties and over-aging resistance. Furthermore, the precipitation of coherent or semi-coherent nano Ni3Ti phases during the aging process positively affects the alloy's yield strength and conductivity. The Oworan and dislocation strengthening mechanisms resulting from nano Ni3Ti phases are the primary mechanisms enhancing the yield strength of Cu–3Ni–1Ti-0.3Zr alloy, contributing approximately 87 %.

Effects of alloying element on the interface stability of fcc-Fe/NbC by first principles investigation

Interfacial segregation engineering is widely used as a means of regulating the strength and toughness of materials. In this paper, the effect of alloying elements on the interfacial segregation and interfacial bonding properties of fcc-Fe/NbC is investigated with the precipitated phase NbC in austenitic heat-resistant steel. The results show that there are eighteen interfacial configurations between the fcc-Fe and NbC phase, and the stability of the interface with Nb terminal is better than that of C terminal according to the calculation results of separation work and interface energy. Al atom is easy to segregate on the surface of austenite, while the alloy elements Mo, Nb, Cr, Ti, Mn, Y and Zr tend to segregate in the austenite matrix. The segregation of alloy elements Mo, Nb, Cr and Ti can enhance the hybridization between the d orbits of Fe and Nb atoms at the interface, thus promoting the bonding strength of the interface, while the segregation of Mn, Al, Y and Zr reduces the covalent interaction of the interface atoms, which weakens the bond strength at the interface. The above results have important practical significance for improving and regulating the composition and interfacial properties of heat-resistant steels.

Study on Microstructure and High-Temperature Mechanical Properties of Al-Mg-Sc-Zr Alloy Processed by LPBF

Al-Mg-Sc-Zr alloy processed via laser powder bed fusion (LPBF) is poised for significant application in aerospace, where its high-temperature capabilities are paramount for the safety and longevity of engineered structures. This study offers a systematic examination of the alloy’s high-temperature tensile properties in relation to its microstructure and precipitate phases, utilizing experimental approaches. The LPBF-processed Al-Mg-Sc-Zr alloy features a bimodal microstructure, with columnar grains in the melt pool’s interior and equiaxed grains along its boundary, conferring exceptional properties. The application of well-calibrated processing parameters has yielded an alloy with an impressive relative density of 99.8%, nearly fully dense. Following a thermal treatment of 350 °C for 4 h, the specimens were subjected to tensile tests at both room and elevated temperatures. The data reveal that the specimens exhibit a tensile strength of 560.6 MPa and an elongation of 11.1% at room temperature. A predictable decline in tensile strength with rising temperature is observed: at 100 °C, 150 °C, 200 °C, and 250 °C; the respective strengths and elongations are 435.1 MPa and 25.8%, 269.4 MPa and 20.1%, 102.8 MPa and 47.9%, 54.0 MPa and 72.2%. These findings underpin the technical rationale for employing LPBF-processed Al-Mg-Sc-Zr alloy in aerospace applications.

Crystallization Behavior of the CaO–SiO2–Al2O3–MgO System Inclusions

The crystallization process of low melting point CaO–SiO2–Al2O3–MgO system inclusions during the continuous casting and hot rolling process greatly affects the deformability of inclusions. The effect of Al2O3 and MgO contents on the crystallization characteristics of CaO–SiO2–Al2O3–MgO system melts representing the typical oxide inclusions in Si–Mn deoxidized steels is systematically investigated. The continuous cooling transformation and time–temperature transformation experiments are carried out. The results reveal that the increase of Al2O3 contents restrains the crystallization process of the melt, whereas the crystallization tendency of the melt is promoted with the increase of MgO contents. The precipitated phases are predominately 2CaO·MgO·2SiO2 and 3CaO·MgO·2SiO2, and the primary crystalline phase is unaffected by the changes of Al2O3 and MgO contents. To obtain low melting point plasticized inclusions with limited crystallization ability, it is recommended to control the Al2O3 and MgO contents greater than 15 wt% and below 5 wt%, respectively. The isothermal treatment is suggested to be controlled within a proper temperature range (1175–1250 °C) to decrease the crystallization kinetics. The oxide system's viscosity change is the limiting kinetic factor in the crystallization process, and it can be utilized to predict the system's crystallization tendency.

Flux-cored arc welding of 316L austenitic stainless steel: the effect of different shielding gas mixtures on microstructural features and weld performance

ABSTRACT Double-pass flux cored arc welding (FCAW) of 316 L austenitic stainless steel was performed using different shielding gas mixtures. Microstructural features and weld performance were evaluated. Based on the Creq/Nieq ratio of fusion zone and cooling rate, different morphologies of ferrite (skeletal, lathy, and dendritic) and austenite with various volume fractions were produced. An increase in Creq/Nieq ratio can increase the strength level because the presence of ferrite in the weld metal acts as a second-phase strengthening agent. On the other hand, ferrite is a suitable place for sigma phase precipitation. Highest joint efficiency resulted in the specimen welded via GTAW. The ductility of welds was ranked as CO2 +Ar shielded FCAW > GTAW > CO2 shielded FCAW > self-shielded FCAW. At room temperature, variation of delta-ferrite content (Creq/Nieq ratio) does not affect toughness. However, an increased amount of CO2 in shielding gas will result in decreased toughness values because of the enhanced formation of oxide inclusions. Increasing CO2 content of shielding gas from 0% to 18% and finally to 100% will result in decreasing toughness values from the highest value of 76J to 40 J and finally the lowest value of 38J.

Precipitation of the gamma prime phase in a Ni-co-based superalloy during different stages of cooling

The cooling precipitation of the gamma primary (γ') phase in a precipitation strengthened Ni-Co-base disk superalloy was investigated by various experimental and analytical methods. The alloy was super-solvus heat treated and then slow cooled to different interrupted temperatures (IT) followed by instant water quenching. It shows that with the IT change, the γ' phase precipitated in different characteristics, such as morphologies, sizes and distributions. Through using three-dimensional atomic probe (3DAP) technique to study the γ and γ' compositions and their interface composition profiles, three types of γ' precipitates, entitled as quenching γ', primary cooling γ' and secondary cooling γ', were identified and their respective precipitation conditions and mechanisms were also discussed. According to the composition gradient across the γ/γ' interfaces and the γ' composition features, the separation mode of these γ' was determined to via the classical nucleation and growth mechanism. In addition, the effects of the γ' forming elements on the nucleation and growth processes of the different generations of γ' were evaluated. It indicates that the diffusion of Ti dominated the primary nucleation while that of Al reigned the following growth and the secondary nucleation.

Tailored precipitation assisted by laser-induced cellular dislocation network structures in Al0.3CoCrFeNi high entropy alloy

Cellular dislocation network structures play a critical role in strengthening metals, while their ability to tailor the precipitation of second-phase particles has long been overlooked. Herein, a novel strategy combining laser surface treatment and two-steps annealing is proposed to produce B2 network structures in the as-cast Al0.3CoCrFeNi high-entropy alloy. Cellular dislocation network structures are first introduced in the plates by the laser surface treatment on both sides, then the L12 phase is precipitated on the wall of the dislocation networks by annealing at 700 °C. During second annealing at 800 °C, previously precipitated L12 precursors provide kinetically preferred sites and element segregation for the precipitation of the B2 phase, finally forming dense B2 network structures within the defect-scarce matrix. Dislocations can easily move inside the network structures, and they are blocked by the B2 particles in the wall areas, thus presenting a superior strength-ductility synergy.

Pulse current enhanced densification and mechanical property of Inconel 718 superalloy fabricated by spark plasma sintering

The Inconel 718 superalloy was fabricated using spark plasma sintering (SPS) technology with varying sintering temperatures and heating rates. The densification and mechanical property of the sintered superalloys were characterized through tensile and compression tests at room temperature, as well as microscopic analyses. The evidence suggests that the plasma generated between the particles results in evaporative melting on the particle surface and plastic deformation of the particle boundaries, accelerating the densification process is by 3∼4 times. Besides, the grain size refinement coefficient affected by pulse current in the holding stage is 0.7–0.8, leading to a significant grain boundary strengthening during SPS process. The dislocation dominated by ball milling and SPS parameters also helps improve the strength and plasticity of the sintered superalloy. The superalloy sintered at 1050 °C with a heating rate of 100 °C/min demonstrated the highest tensile and compressive fracture strengths, measuring 1410 MPa and 1983 MPa, respectively, with the tensile and compressive yield strength of 712 MPa and 1557 MPa, respectively. Lower sintering temperatures or higher heating rates results in lower levels of densification and decreased strength. In addition, plasticity is reduced at higher sintering temperatures or lower heating rates due to excessive precipitation of brittle phases.

Identification of nano-sized precipitates in CLAM steel induced by 3.5 MeV Fe13+ ion irradiation

Nano-sized precipitate phases in normalized-and-tempered CLAM steel (HEAT-0912) before and after 3.5 MeV Fe13+ ion irradiation at 400 °C to 0.61, 1.29 and 2.77 dpa were studied using transmission electron microscope and high-resolution transmission electron microscope. Six types of nanoprecipitate phases based on Cr23C6, TaC, Ta3C2, VC, Cr7C3, and V2C were identified in unirradiated steel. During irradiation, a large number of nanoprecipitates uniformly distributed in the matrix occurred, and the number density of nanoprecipitates initially increased and subsequently decreased with increasing the irradiation dose. Nanoscale Cr-rich M23C6, V-rich MX and M2X phases but no nanoscale phases based on TaC, Ta3C2 and Cr7C3 were identified in the steel irradiated up to 2.77 dpa. After irradiation, five types of irradiation-induced nanoscale new phases were identified in the irradiated steel. These include Fe-rich M3X2 (Cr3C2 types I and II) carbonitrides with the same simple orthorhombic lattice and totally different lattice parameters (approximately a/b/c = 1.146/0.552/0.2821 nm and 0.285/0.925/0.696 nm), Fe-rich M2C, M3C and M5C2 carbides, but the occurrence of which under irradiation varied with the irradiation dose. Fe-rich M3X2 (Cr3C2 type I) and Fe-rich M5C2 phases were identified in the steel irradiated up to 1.29 dpa and only to 2.77 dpa, respectively. Fe-rich M2C and M3C in addition to Fe-rich M3X2 (Cr3C2 type II) phases were identified in the steel irradiated up to 2.77 dpa. The irradiation-induced Fe-rich M3X2 (Cr3C2 type I & II), M5C2 and M2C precipitates appear to be identified, for the first time, in reduced activation ferritic/martensitic steels including CLAM steel. The formation mechanism of these irradiation-induced precipitate phases is also discussed.

Engineered loose nanofiltration membrane for efficient dye/salt separation by starting from poly(ether sulfone) powder modification

Loose nanofiltration (LNF) is increasingly considered as the powerful technique for dye desalination due to its clear advantages at energy efficiency, selectivity and low pollution. But the membrane materials for loose nanofiltration process still suffer from the low permeance, unsatisfactory selectivity, membrane fouling and high cost. Herein, we propose a new three-step route to fabricate efficient poly(ether sulfone) (PES) LNF membrane, which starts from PES powder modification via mutual radiation-induced grafting polymerization and ensues immersion precipitation phase inversion and amination processes. The obtained PES-based LNF membrane possessed a thinner skin layer and an unusual irregular vesicular pore structure in sublayer instead of the finger-like macrovoids of conventional PES membrane. Thus, it achieved larger filtration permeance (35.5 L m–2 h−1 bar−1), high dye rejection (93.7 % to Congo Red) but low salt rejection (2.9 % to NaCl) during the filtration process of Congo red-containing saline water. It also showed excellent separation stability at high operation pressure and tolerance to acidic, alkaline and chlorine-oxidative conditions. Therefore, such a three-step strategy could endow the PES membrane with both loose and thinner skin layer in a reliable and scalable way, enlightening the development of high-performance LNF membrane for wastewater treatment and resource recovery.

Anticipating how rain-on-snow events will change through the 21st century: lessons from the 1997 new year’s flood event

The California-Nevada 1997 New Year’s flood was an atmospheric river (AR)-driven rain-on-snow (RoS) event and remains the costliest in their history. The joint occurrence of saturated soils, rainfall, and snowmelt generated inundation throughout northern California-Nevada. Although AR RoS events are projected to occur more frequently with climate change, the warming sensitivity of their flood drivers across scales remains understudied. We leverage the regionally refined mesh capabilities of the Energy Exascale Earth System Model (RRM-E3SM) to recreate the 1997 New Year’s flood with horizontal grid spacings of 3.5 km across California, with forecast lead times of up to 4 days, and across six warming levels ranging from pre-industrial conditions to +3.5∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$+3.5\\,^\\circ$$\\end{document}C. We describe the sensitivity of the flood drivers to warming including AR duration and intensity, precipitation phase, intensity and efficiency, snowpack mass and energy changes, and runoff efficiency. Our findings indicate current levels of climate change negligibly influence the flood drivers. At warming levels ≥1.7∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\ge 1.7\\,^\\circ$$\\end{document}C, AR hazard potential increases, snowpack nonlinearly decreases, antecedent soil moisture decreases (except where the snowline retreats), and runoff decreases (except in the southern Sierra Nevada where antecedent snowpack persists). Storm total precipitation increases, but at rates below warming-induced increases in saturation-specific humidity. Warming intensifies short-duration, high-intensity rainfall, particularly where snowfall-to-rainfall transitions occur. This study highlights the nonlinear tradeoffs in 21st-century RoS flood hazards with warming and provides water management and infrastructure investment adaptation considerations.