Boundary Precipitation Research Articles

Ageing response and microstructural evolution of biodegradable Zn-1.5Cu-1.5Ag alloy

In this study, the age-hardening response and microstructural evolution of an as-extruded biodegradable Zn-1.5Cu-1.5Ag (wt.%) alloy during ageing at 25 ℃, 100 ℃, 150 ℃ and 200 ℃ are studied. The age-hardening response is generally weak, and the largest hardness increment is observed after ageing at 150 ℃ for 24 h. Discontinuous precipitation (DP) and continuous precipitation (CP) occur competitively during ageing at 150 ℃ or 200 ℃, while only DP is observed during ageing at 25 ℃ or 100 ℃. All the precipitates formed through DP and CP are identified as ε-(Ag, Cu)Zn4 that has a hexagonal structure. Analysis of possible strengthening mechanisms shows that grain boundary strengthening and precipitation hardening contribute to the major part of yield strength in the as-extruded condition. Ageing treatments generate a limited increment in yield strength due to the small difference between the hardness of ε-(Ag, Cu)Zn4 and the Zn matrix and the reduced solid solution strengthening effect. Artificial ageing at 150 ℃ for 48 h effectively improves the stability of the mechanical properties of the as-extruded Zn-1.5Cu-1.5Ag alloy. This process fully depletes the excessive solutes in the supersaturated Zn matrix, ensuring that the alloy maintains consistent mechanical properties when stored at room temperature.

Near-theoretical strength and deformation stabilization achieved via grain boundary segregation and nano-clustering of solutes

Grain boundary hardening and precipitation hardening are important mechanisms for enhancing the strength of metals. Here, we show that these two effects can be amplified simultaneously in nanocrystalline compositionally complex alloys (CCAs), leading to near-theoretical strength and large deformability. We develop a model nanograined (TiZrNbHf)98Ni2 alloy via thermodynamic design. The Ni solutes, which has a large negative mixing enthalpy and different electronegativity to Ti, Zr, Nb and Hf, not only produce Ni-enriched local chemical inhomogeneities in the nanograins, but also segregate to grain boundaries. The resultant alloy achieves a 2.5 GPa yield strength, together with work hardening capability and large homogeneous deformability to 65% compressive strain. The local chemical inhomogeneities impede dislocation propagation and encourage dislocation multiplication to promote strain hardening. Meanwhile, Ni segregates to grain boundaries and enhances cohesion, suppressing the grain growth and grain boundary cracking found while deforming the reference TiZrNbHf alloy. Our alloy design strategy thus opens an avenue, via solute decoration at grain boundaries combined with local chemical inhomogeneities inside the grains, towards ultrahigh strength and large plasticity in nanostructured alloys.

Study on the effect of temperature on the microstructure and mechanical properties of as-cast CoCr2Ni3.5VAl1.5Ti high-entropy alloy

This study investigates the microstructure and mechanical properties of a CoCr2Ni3.5VAl1.5Ti high entropy alloy (HEA) annealed at 500 °C, 700 °C, 900 °C and 1100 °C for 6 h. The alloy was prepared using a vacuum induction melting furnace and annealed at the specified temperatures for 6 h. It was then characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron backscatter diffraction (EBSD). The results indicate that with increasing annealing temperature, the alloy's phase structure transitions gradually from multiphase (fcc, bcc, hcp) to predominantly fcc phase, with relatively stable elemental distributions. Annealing at 500 °C–900 °C mainly strengthens the alloy through precipitates and dislocation strengthening, whereas at 1100 °C, strengthening occurs through grain boundary strengthening and precipitate growth, enhancing the material's strength and ductility. The alloy exhibits optimal comprehensive performance after annealing at 1100 °C. This study provides important insights for optimizing the heat treatment process of HEAs.

Exploring the effect of Cr and Mn on the intrinsic strength of the tensile properties of FeCoNi, FeCoNiMn, FeCoNiCr, and FeCoNiCrMn multi-principal element alloys using in-situ EBSD

As the composition elements in multi-principal element alloys increase, it can bring excellent mechanical properties. However, the strengthening mechanism of the additional element is still unclear. In this work, we establish a method based on the in-situ EBSD technology to explore the possible effect of additional elements on the intrinsic strength of tensile properties. We prepared four different multi-principal element alloys, including FeCoNi, FeCoNiMn, FeCoNiCr, and FeCoNiCrMn with similar initial status. We systematically investigated the evolution of the microstructure, dislocation density, twin boundary, grain size, and element distribution during the tensile process by in-situ EBSD and EDS. By carefully analyzing the results of four different multi-principal element alloys, the strength effects of the solid-solution hardening, grain-boundary hardening, twin boundary hardening, precipitate hardening, and dislocation hardening were peeled. The effect of the Cr and Mn element addition on the intrinsic strength can be explored. It is found that the element addition indeed increases the intrinsic strength from quaternary to quinary but not very clear from ternary to quaternary no matter Cr or Mn, which indicated that the intrinsic strength was more related to the number of elements in the alloy than to which element was present. This can be explained using the mixing entropy theory, which states that the intrinsic strength is enhanced when the mixing entropy is over a threshold between the MEA and HEA. This paper presents a method to study the individual factors affecting the tensile properties, which can help other researchers to better investigate HEA.

Picturing Global Substorm Dynamics in the Magnetotail Using Low‐Altitude ELFIN Measurements and Data Mining‐Based Magnetic Field Reconstructions

AbstractA global reconfiguration of the magnetotail characterizes substorms. Current sheet thinning, intensification, and magnetic field stretching are defining features of the substorm growth phase and their spatial distributions control the timing and location of substorm onset. Presently, sparse in‐situ observations cannot resolve these distributions. A promising approach is to use new substorm magnetic field reconstruction methods based on data mining, termed SST19. Here we compare the SST19 reconstructions to low‐altitude electron losses and fields investigation (ELFIN) measurements of energetic particle precipitations to probe the radial profile of the equatorial magnetic field curvature during a 19 August 2022 substorm. ELFIN and SST19 yield a consistent dynamical picture of the magnetotail during the growth phase and capture its key features such as the formation of a thin current sheet and its earthward motion. Furthermore, they resolve a “checkmark” pattern of isotropic electron precipitation boundaries in the time‐energy plane, consistent with earlier observations but now over a broad energy range. It is shown that in the growth phase, the mismatch between SST19 and ELFIN latitudes is much less than one degree, the capability unattainable for any other empirical or first‐principles model.

Effect of intermittent non-isothermal aging on the microstructure and properties of Al–Zn–Mg–Cu alloy

The proposition of an intermittent non-isothermal aging (IM-NIA) is an innovative approach to address the challenge of balancing the mechanical properties and corrosion resistance of Al–Zn–Mg–Cu alloys. The effects of IM-NIA on the hardness, corrosion resistance and microstructure morphology of Al–Zn–Mg–Cu alloys were investigated by hardness test, intergranular corrosion test (IGC), exfoliation corrosion test (EXCO), electrochemical corrosion test and combined with transmission electron microscopy (TEM) observation. The results showed that the hardness of the alloy was the highest at 186HV after intermittent post-tempering to 180 °C (IM-H180). The intergranular corrosion depth is the smallest, the corrosion rate is the slowest, and the exfoliation corrosion rating is EA. In addition, the alloy matrix precipitated phase has the smallest average diameter, the highest volume fraction, the strongest ability to repair the passivation film, and the strongest resistance to Cl− erosion; At the same time, the grain boundary precipitation phase is intermittent and multilinear parallel distribution, PFZ is the widest, hindering the anodic corrosion channel, slow corrosion progress and improve corrosion resistance.

Microstructure and tensile properties of Y2O3-dispersion strengthened CoCrFeNi high entropy alloys prepared via mechanical alloying using pre-alloyed powder

Nano-Y2O3-dispersion strengthened CoCrFeNi high entropy alloys are fabricated via mechanical alloying and spark plasma sintering using high purity elemental powders or pre-alloyed CoCrFeNi powder. All the alloys show an FCC matrix incorporated by small amount of BCC Cr-rich segregations, whose brittle nature is detrimental to the mechanical properties of the alloys. It has been found that using pre-alloyed powder significantly suppresses the formation of the Cr-rich phase, and its size and volume fraction can be further reduced by increasing the rotation speed of ball-milling during mechanical alloying. Besides, the grain refinement is also achieved under a higher rotation speed. Y2O3 nanoparticles with a number density of 1.8 × 1022 m−3 and an average diameter of 11.0 ± 7.3 nm are uniformly distributed in the alloy that produced from pre-alloyed powder under the rotation speed of 350 rpm during ball-milling. These Y2O3 nanoparticles share coherent interface with the FCC matrix, indicating the in-situ precipitation mechanism. Due to a good combination of grain boundary strengthening, dislocation strengthening and precipitation strengthening, this ODS high entropy alloy possesses a yield strength of 1281 MPa at room temperature.

Altering tensile and crack initiation behavior in a metastable β titanium alloy via designing grain size and precipitates

Microstructure can play a vital role in defining mechanical properties of metallic materials. To elucidate this correlation in the case of Ti–15Mo–3Nb–3Al-0.2Si (TB8) alloy, herein, we designed various microstructures via heat treatment exploring the effects of grain size, precipitates and segregation on crack initiation behavior during tensile tests in metastable β-Ti alloy. After solution treatment at 830 °C, the TB8 alloy with equiaxed β grain displayed a good fracture elongation of 30.2 ± 0.63%. The adiabatic shearing band and β→α phase transformation were activated to increase the compatible deformation capability during tensile testing; however, the phase transformation caused the stress concentration in the boundary, resulting in crack initiation. For the samples prepared using solution and low aging at 440 °C, large grain, elements segregation at grain boundary and incomplete precipitates induced a slight reduction in ultimate tensile strength and elongation. After solution and aging at 520 °C, the short-rod or/and lamellar α phase precipitated in β grain effectively enhancing ultimate tensile strength (1398.71 ± 15.6 MPa). The increased boundaries provided the interface or precipitation strengthening effect, but high-density dislocations were also accumulated at the β/α interface, causing unstable deformation and crack initiation. These findings advance our understanding of the correlation between microstructure and crack initiation, and provide a basis for designing and customizing the mechanical properties of metastable β-Ti alloy.

Preparing gradient microstructure to achieve enhanced performance in GH4586 superalloy: Experiments and models

In this present study, a combined method of controlling strain deformation (CSD) and gradient-temperature heat treatment (GTHT) was adopted to prepare gradient microstructure in GH4586 superalloy. Consequently, it brought enhanced tensile strength from 1313.1±18.7 MPa at intermediate transition (IT) region to 1506.3±15.7 MPa at high-strain and low-temperature (HS-LT) region, presenting an improvement of 11.6%. And it also enhanced fracture toughness from 77.7±0.3 MPa⋅m1/2 at IT region to 86.7±3.7 MPa⋅m1/2 at low-strain and high-temperature (LS-HT) region, presenting an improvement of 14.7%. The formation of gradient microstructure along the longitudinal direction of CSD+GTHT-treated sample was thoroughly investigated from perspectives of precipitates distribution, activated slip systems and dislocations evolution. During CSD, the size and volume fraction of γ′ precipitates decreased under the effect of strain-induced dissolution behavior. The activation of (1‾ 11)[101] and (11‾ 1)[011] slip systems dominated dislocation movement at each region and there retained increasing dislocation density due to more extensively activated slip systems at HS region. During GTHT, the high-density dislocations promoted recrystallization while the concentratedly distributed γ′ precipitates obstructed movement of recrystallized front, leading to formation of heterogeneous structure with high-density grain boundaries and dislocations at HS-LT region. Finally, a model reflecting the effect of grain boundary strengthening, precipitation strengthening and dislocation strengthening on mechanical property of gradient microstructure was established and successfully applied to property prediction of GH4586 superalloy.

Dependence of the main ionospheric trough position on local time, longitude and geomagnetic activity in the southern winter hemisphere

Based on the meticulous identification of ionization troughs, performed earlier from the CHAMP satellite data, twoadditional issueswereresolved: (1) the longitudinal effect characteristics in the position of the main ionospheric trough (MIT) were corrected, and (2) for the first time,the dependence of theMITposition on geomagnetic activity was determined foralllocaltime hours. A large dataset from the CHAMP satellite in the southern winter hemisphere under high solar activity was utilized. According to the refined data the amplitude of the longitudinal effect in the MITposition changes from ∼ 3° to ∼ 5° in the course of the day. The shape of the longitudinal effectvarieswith local time, however, the MIT in the eastern hemisphere isconsistentlylocated at higher latitudes than in the western hemisphere. The main reason for the longitudinal effect is the dependence of the equatorward boundary of auroral diffuse precipitation on the tilt angle of the Earth’s dipole. The dependence on geomagnetic activitywas determined as a linear regression ΛT = Λ0 − aKp, where Λ is the geomagnetic latitude, and the Kp indexisconsidered for the previous6 h. The latitude Λ0 and coefficient a exhibited pronounced dependence on local time, with Λ0 increasing and a decreasing when moving from night to day. Because the amplitude of the longitudinal effect decreases with increasing magnetic activity, the value of a alsodependson longitude. Consequently, coefficienta wasdetermined separatelyforthe eastern and western hemispheres. Theaveragevaluesof a vary from 1.3 − 1.4° during the day to 1.8 − 1.9° at night. Thedifference between theeastern and western hemispheres is ∼ 0.3°.

Experimental investigations on influence of processing parameters on the microstructure and properties of AM-printed stainless steel

ABSTRACT The current study has investigated the mechanical properties and microstructure of the DMLS processed 316L experimentally by varying process parameters and solution annealing as a post-processing technique. The feedstock material characteristics, laser power input, layer thickness, scanning velocity, hatch spacing, and building direction are important factors to consider. The modified microstructure not only affects mechanical performance and corrosion resistance but also alters the specimen's properties. An analysis of the powder feedstock and density measurement has been conducted. The samples were subjected to tensile testing, hardness testing, and microstructural analysis. According to the Taguchi analysis findings, the most significant parameter affecting product quality was layer thickness. The observation of grain boundary precipitation in a few samples could be reversed through solution annealing. The results of this study will assist in determining the optimal process parameters for achieving the desired mechanical properties.

Hot deformation behavior and microstructural evolution of a new type of 7xxx Al alloy

Optimizing the thermal deformation parameters of Al alloys is beneficial for achieving grain refinement, avoiding microscopic defects in materials, and significantly enhancing the mechanical properties of Al alloys. In this study, the hot deformation behavior of a new type of 7xxx Al alloy was investigated through hot compression tests at strain rates of 10−3-1 s−1 and temperatures of 250–420 °C. The constitutive equation was successfully established using the hyperbolic sine form of the Arrhenius equation, accurately describing the flow stress. The hot processing map was obtained by overlaying the power dissipation map and the instability map, determining the optimal hot working parameters to be in the range of 325–373 °C, 0.45–1 s−1. In the safe region, dynamic recovery (DRV) and dynamic recrystallization (DRX) were predominant. The instability in the low-temperature region was attributed to the grain boundary pinning effect caused by grain boundary precipitation, while the instability in the high-temperature region was associated with local shear bands induced by uneven plastic strain. The hot processing map establishes a good connection with the microstructural evolution of the new type of 7xxx Al alloy under different hot deformation parameters.

Unveiling the precipitation behavior and mechanical properties in G-phase strengthened CrFe2Ni2Ti0.2Six multi-principal element alloys

In order to develop Co-free CrFeNi based multi-principal element alloys (MPEAs) with good synergies between strength and plasticity, the effects of Si content on the microstructures and mechanical properties of CrFe2Ni2Ti0.2Six (x = 0, 0.125, 0.25, 0.375, 0.5 and 0.625) MPEAs are studied in this work. The results show that the addition of Si induces a phase transformation from a single-phase face-centered cubic (FCC) structure to a dual-phase structure, comprising an FCC solid solution phase and G-phase. The outcomes from phase formation theory and phase diagram calculations (CALPHAD) also confirm that CrFe2Ni2Ti0.2Six MPEAs are prone to form dual-phase structures. With increasing Si content, the yield strength and hardness of the alloys increase by 47.2 % and 57.3 %, respectively, while still maintaining a strain of 34.2 %, which is indicative of commendable overall mechanical properties. This is ascribed to the coherence between FCC matrix and G-phase, enabling an enhancement in strength concurrently with the retention of considerable plasticity. Moreover, grain boundary strengthening and precipitation strengthening play a dominant role in the strengthening of CrFe2Ni2Ti0.2Six MPEAs. The present work offers new insights for the further development of high-performance non-metallic MPEAs, so as to achieve a combination of targeted microstructures and excellent properties.

Effect of aging treatment on microstructure and corrosion properties of Al-Cu-Mn-Si-Mg-Er-Zr alloy

The microstructure, mechanical properties and intergranular corrosion resistance of Al-Cu-Mn-Si-Mg-Er-Zr alloy with squeeze casting in the peak aging state at different temperatures were studied. The alloy was aged at 165 °C, 175 °C and 185 °C, and reached peak aging at 18 h, 12 h and 8 h respectively, among them, the alloy treated with 175 °C/12 h aging has the highest hardness, reaching 149 HV, and the yield strength is also the highest, which is 387 MPa. It is because the Q phase precipitated during the aging process of the alloy provides a heterogeneous nucleation site for the θ′ phase, the average size of the θ′ phase is 73.38 nm. The intergranular corrosion depth of the alloy after aging treatment at 175 °C/12 h was the deepest, reaching 284.91μm. At this time, the width of precipitation-free zone(PFZ) is the widest in the grain boundary microstructure, which is 92.21 nm, and the grain boundary precipitation phase is continuously distributed.

Achieved strength-plastic trade-off in HfMoNbTaTi refractory high-entropy alloy via powder metallurgy process

The practical application of refractory high-entropy alloys (RHEAs) has been limited by their brittleness at room temperature. This study prepared fine-grained HfMoNbTaTi refractory high-entropy alloys using a powder metallurgy process combining mechanical alloying (MA) and spark plasma sintering (SPS). This method effectively addresses the issue of room temperature brittleness and achieves a favorable balance between strength and plasticity. The resulting sintered alloy comprises two body-centered cubic (BCC) solid solution matrices and a range of nanoprecipitates, including the γ-phase, σ-phase, and α-phase. With increasing sintering temperature, the average grain size increased from 0.45 μm (at 1400 °C) to 4.56 μm (at 1700 °C). Simultaneously, the content of the γ-phase gradually decreases due to the greater influence of mixing entropy. Under quasi-static loading, the fine-grained multiphase structure not only benefits from grain boundary strengthening and precipitation strengthening effects, but also enhances the deformation uniformity, ultimately improving both the strength and plasticity. At 1450 °C, the sintered alloy exhibited a compressive yield strength of 2325 ± 8.40 MPa and a plastic strain of 26.44 ± 1.17 %. These values represent a 35.73 % increase in yield strength and a 120.33 % increase in plastic strain compared to those of the as-cast alloy. The deformation process at room temperature is mainly governed by the multiplication of screw dislocations and cross-slips. In the middle and late stages of deformation, the grains exhibit a preferred orientation, further enhancing the plastic strain. In summary, this study presents a practical approach for overcoming the issue of room temperature embrittlement in RHEAs.

Effects of grain boundary chemistry and precipitate structure on intergranular corrosion in Al-Mg-Si alloys doped with Cu and Zn

Al-Mg-Si alloys are known as structural materials and are primary alloys in the automotive industry to achieve weight reduction. Shifting toward sustainability, lower energy consumption, and less CO2 emission necessitates recycling. However, the unavoidable accumulation of scrap-related impurities, e.g., Cu and Zn, during the recycling process can influence corrosion resistance of recycled alloys. The results show that Al-Mg-Si alloys containing 0.05 wt% Cu exhibit low intergranular corrosion resistance. The intergranular corrosion resistance of these alloys is notably improved by adding 0.06 wt% Zn. Low concentrations of Cu and Zn are found to strongly affect the crystal structure of hardening precipitates.

Orientation dependent grain boundary precipitate distribution and the weakened pinning effects on domain walls in sintered Sm2Co17-type magnet

In a typical sintered multi-component Sm2Co17-type magnet with strong fiber texture, we show that the distributions of grain boundary precipitates (GBPs) are heavily dependent on the grain boundary (GB) geometry with respect to the texture direction, which has significant effects on domain wall pinning. Results demonstrate that the continuous GBPs turn into discrete upon the angle between {0001} planes and GB increases from 0° to 90°, meanwhile the GBPs thickness and precipitation free zones (PFZs) width both increase linearly by a factor of 2.5–4. Transmission electron microscopy (TEM) reveals that the GBPs are alternatively stacked Cu-rich SmCo5 and Zr-rich Smn+1Co5n−1 (n = 2,3,4) compounds, while the PFZs are composed of 2:17R and intermediate 2:17R’ phases. Atomic-level elemental mappings and first-principles calculations indicate that Cu exists at the Co-2c site in the SmCo5 forming SmCo3Cu2 and Zr locates at the dumbbell Sm-6c sites in the Smn+1Co5n−1. The symbiotic GBPs have orientation relationships of [0001]GBPs//[0001]2:17R and [101¯0]GBPs//[21¯1¯0]2:17R. The formation of anisotropic GBPs is owing to the strong fiber texture, i.e., the larger angle between {0001} planes and GBs, the more {0001} diffusion channels for atoms to GBs, resulting in discrete and thick GBPs. In-situ Lorentz TEM shows that the domain walls interrupted by GBPs migrate easily under applied magnetic fields. Possible approaches to enhance the magnetic hardness via tuning the GBs are proposed.

Effect of total content of Zn and Mg on microstructure and mechanical properties of Al-3.2xZn-xMg-1.66Cu-0.15Zr aluminum alloy sheet

The effects of total Zn and Mg content on the microstructure, tensile properties, and fatigue properties of Al-3.2xZn-xMg-1.66Cu alloy sheets were systematically investigated after aging at 120 °C for 24 h. As the total content of Zn and Mg increased, the recrystallized grains were gradually refined, and the types of precipitate particles did not change, all of which comprised Guinier Preston (GP) zones and η′ metastable-phase particles, whereas both the number and volume fraction of η′-phase particles increased gradually, where the particles were first coarsened and then refined. The η′-phase particles were largest (∼8.2 nm) in the alloy with the total Zn and Mg content of 5.15 wt.%. The grain boundary precipitate (GBP) gradually coarsened and the width of the precipitates free zone (PFZ) gradually decreased. When the total content of Zn and Mg was increased from 2.61 to 11.40 wt.%, the yield strength and tensile strength increased from 173 and 309 MPa to 554 and 620 MPa, respectively, whereas the elongation decreased from 29.9% to 8.5%. However, the fatigue strength of the alloy sheet first decreased from 149 to 119 MPa and then increased to 183 MPa under the condition of R = 0.1. The fatigue strength of the alloy sheet with total Zn and Mg contents of 5.15 and 11.40 wt.% were the lowest one and the highest one, respectively, and the latter was 54% higher than the former.

Ultrasonic peening-waterjet composite surface modification of 7075-T6 aluminum alloy for residual stress release and transformation mechanism

The release and transformation mechanism of residual stress contributes to the improvement of metal materials' processing and performance, enhancing their structural stability, surface integrity, and fracture resistance. This paper focuses on the Ultrasonic Impact Treatment-Solid Particle Entrainment by Waterjet (UIT-SPEWJ) composite surface modification of 7075-T6 aluminum alloy, investigating the effects of UIT-SPEWJ process parameters (jet pressure and target distance) on the alloy's surface quality, roughness, microhardness, residual stress, and the evolution mechanism of microstructure. The results indicate that the 7075-T6 aluminum alloy modified by UIT-SPEWJ mainly exhibits a "meteorite crater" effect, accompanied by significant smearing and ploughing phenomena. Surface roughness shows a trend of first decreasing and then increasing with the rise of jet pressure and target distance. The minimum surface roughness, 0.852 μm, is achieved at a jet pressure of 25 MPa and a target distance of 7.5 mm. The microhardness of the samples modified by UIT-SPEWJ gradually decreases from the surface to the substrate with increasing depth. The hardened layer depths of the samples UIT-SPEWJ-1–6 after modification are approximately 174 μm, 226 μm, 200 μm, 196 μm, 176 μm, and 172 μm, respectively. After UIT, SPEWJ, and UIT-SPEWJ surface modifications, the surface of 7075-T6 aluminum alloy mainly exhibits compressive residual stress (CRS). The surface residual stress σ_srs of samples modified by UIT and SPEWJ are approximately 195.161 and 215.752 MPa, respectively. The surface residual stresses of UIT-SPEWJ-1–6 samples are significantly improved to 277.089, 529.499, 393.615, 459.261, 368.084, and 220.635 MPa, respectively, with UIT-SPEWJ-2 sample having the highest surface residual stress, which is 2.7 and 2.4 times that of UIT and SPEWJ modified surfaces. Samples modified by UIT-SPEWJ present significant dislocation phenomena, and the precipitated phases mainly include the needle-like metastable phase η', as well as the equilibrium phase η (MgZn2) with a rod-like structure. At lower jet pressures and larger target distances, the 7075-T6 aluminum alloy exhibits a continuous PFZ with a size of approximately 12–23 nm. As jet pressure increases and target distance decreases, discontinuous grain boundary precipitate bands appear, sized around 8–17 nm. Moreover, when the jet pressure is 25 MPa and the target distance is 7.5 mm, the grain boundary precipitated phases are more dispersed.

Irrigation impact on boundary layer and precipitation characteristics in Weather Research and Forecasting model simulations during LIAISE‐2021

Irrigation impact on boundary layer and precipitation characteristics in Weather Research and Forecasting model simulations during LIAISE‐2021