Heterogeneous Nucleation Research Articles

Oxygen-induced decomposition of the body-centered cubic HfNbTaTiZr high-entropy alloy

The factors affecting the stability of an initially single-phase body-centered cubic (BCC) HfNbTaTiZr solid solution are investigated by heat treatments at 900 °C up to 1000 h in different atmospheres. The BCC solid solution is stable but oxygen (O) contamination originating from the aging atmosphere leads to the co-precipitation of an O-enriched hexagonal close-packed (HCP) Hf-Zr-rich phase and a second Nb-Ta-rich BCC phase. As O from the atmosphere diffuses from the surface to the core of the sample at a much faster rate along grain boundaries than through the grain interior, this results in an inhomogeneous distribution of precipitates, which formed at grain boundaries by a monotectoid reaction. In contrast, coincidence-site-lattice boundaries are not affected by this transformation owing to their lower diffusivities and lower capacity for heterogeneous nucleation. Similar phases were observed in a HfNbTaTiZr enriched with 3 at.% O, thus confirming the role of oxygen in phase stability.In both alloys, the orientation relationship (OR) between the HCP and BCC phases is predominantly of Burgers type but our analyses further revealed the presence of two minor ORs. More interestingly, both alloys exhibit rod-shaped HCP precipitates in contrast to the plate-shaped precipitates observed in conventional Ti and Zr-based alloys. This result can be rationalized by calculations of elastic strain energy density, which suggest that the rods should grow along 〈100〉BCC to minimize the elastic strain energy. Deviations of up to 20° from this theoretical direction were observed and are likely related to relaxation by misfit dislocations or by plastic deformation.

Manipulation of the α-phase precipitation behavior through dual-aging treatment and its correlation with mechanical properties in a metastable β titanium alloy

The precipitation behavior of α-phase and its crucial impact on the mechanical properties have been investigated in a metastable β-type Ti-4Al-6V-5Mo-3Cr-1Zr (wt%, Ti-46531) alloy. Through dedicated design of dual-step aging conditions, the nucleation mechanism, number density and morphology of the secondary α-phase precipitates can be modulated. After the first-step aging treatment at 300 °C for 5−100 h, isothermal ω-phase (ωiso) particles precipitate and are uniformly dispersed in the β-phase matrix, with their number density gradually increasing with aging time. The subsequent second-step aging treatment at 600 °C for 2 h leads to the rapid dissolution of ωiso and the precipitation of α-phase through the classical nucleation process with a steady number density. Lowering the second-step aging temperature to 520 °C promotes the heterogeneous nucleation of the α-phase with the assistance of uniformly dispersed ωiso particles. This leads to a significant increase in the number density of α-phase precipitates. Consequently, the maximum yield strength increases from 1296 MPa for samples aged at 600 °C to 1623 MPa for samples aged at 520 °C. The precipitation of α-phase serves a dual role in enhancing the yield strength, both by providing precipitation strengthening and by increasing dislocation density. The contribution to yield strength enhancement from the former effect is considerably more substantial than the latter. This work underscores the crucial role of α-phase number density in determining the strength of metastable β titanium alloys, offering new insights into the tailoring of microstructures and mechanical properties through dual-aging treatments.

In situ growth and crystallization behavior of PP crystals induced by CF under supercritical N2

High-performance carbon fiber reinforced polypropylene (PP/CF) composite foams were successfully prepared using supercritical N2 as a physical blowing agent, significantly reducing raw material usage. However, the incorporation of supercritical N2 complicates the crystallization behavior of PP/CF, subsequently affects their property. Herein, this study proposes to prepare PP/CF films by solution method and observe in situ growth and crystallization behavior of PP crystals induced by CF under supercritical N2 for the first time. Numerous nucleation sites are formed in CF under supercritical N2, facilitating transcrystalline formation at the interface and confirming CF's potent heterogeneous nucleation capability. The surface tension effect of CF was visualized for the first time, noting the transformation of spherulites into dendritic structures. This transformation, becoming more pronounced with successive isothermal crystallizations, is attributed to changes in the rheological behavior of the PP melt. Furthermore, the research elucidates the mechanism behind CF-induced transcrystalline formation and the periodic growth of the crystal front under supercritical N2. A 20%CF addition reduced grain size by 41.2 % and increased grain density by 2.7 times at 130 °C. However, a higher CF content raises the interfacial free energy required for nucleation, leading to a slower grain growth rate. This work not only addresses the gap in understanding fiber-induced crystallization under supercritical gases but also lays a theoretical foundation for the crystallization behavior of other fibers under similar conditions. It provides critical insights for developing fiber-reinforced composite microcellular plastics with superior properties.

Sex-Specific changes in stress circuitry of the nucleus tractus solitarius following food deprivation in two rat strains

Food deprivation is used in many experimental models and is becoming increasingly prevalent in human diets. The impact of food deprivation on specific brain regions, including the nucleus of the tractus solitarius (NTS), a region that is involved in hunger and satiety sensing, remains to be determined. The NTS is a heterogeneous nucleus that includes corticotropin releasing factor receptor 1 (CRF1) neurons. CRF1 is implicated in both stress and appetite regulation, but the effects of food deprivation on CRF1 NTS neurons are unclear. We used immunofluorescence to examine the effects of 24-hour food deprivation on NTS activity in male and female Sprague-Dawley (SD) rats and CRF1-cre rats using cFos, an immediate early gene and neuronal marker of activation. NTS activity was increased in food deprived male but not female SD rats. In food deprived CRF1-cre rats, males had an increased proportion of active CRF1 + neurons with no change in females. In CRF1-cre rats, increased global NTS activity was observed in food deprived and refed males. Activation of CRF1 + neurons was also increased after deprivation but was reduced by refeeding. In females, food deprivation decreased global NTS activity that was then increased by refeeding, while CRF1 activity was unchanged.Collectively, these data suggest the NTS is differentially activated after food deprivation in a sex-specific manner, whereby males are more sensitive than females. These results provide insight into the role of brainstem stress circuitry in changes associated with conditions including intermittent fasting and eating disorders like anorexia.

Surface effects on functional amyloid formation.

Functional amyloids formed by the protein FapC in Pseudomonas bacteria are key structural components of Pseudomonas biofilms, which mediate chronic infections and also contribute to antimicrobial resistance. Here, we combine kinetic experiments with mechanistic modelling to probe the role of surfaces in FapC functional amyloid formation. We find that nucleation of new fibrils is predominantly heterogeneous in vitro, being catalysed by reaction vessel walls but not by the air/water interface. Removal of such interfaces by using microdroplets greatly slows heterogeneous nucleation and reveals a hitherto undetected fibril surface-catalysed "secondary nucleation" reaction step. We tune the degree of catalysis by varying the interface chemistry of the reaction vessel and by adding nanoparticles with tailored surface properties that catalyse fibril nucleation. In so doing, we discover that the rate of nucleation is controlled predominantly by the strength with which FapC binds to the catalytic sites on the interface, and by its surface area. Surprisingly, neither primary nucleation rate nor catalytic site binding strength appear closely correlated to the charge and hydrophilicity of the interface. This indicates the importance of considering experimental design in terms of surface chemistry of the reaction container while also highlighting the notion that fibril nucleation during protein aggregation is a heterogeneous process.

Effects of trace nano-TiB2 particles and multiple cooling rates on microstructure and properties of Al-4.5Cu alloy

Ceramic particles and cooling rates have important effect on the Strength and plasticity of aluminum-based materials. In this paper, the microstructure and mechanical properties of Al-4.5Cu alloy were controlled by adding ultra-trace amounts of in-situ synthesized TiB2 particles and multiple cooling rates. The results show, that the average size of TiB2 particles is about 86.35 nm. The lattice dis-registry between TiB2 and α-Al was calculated to be 4.5 %, the TiB2 particles can be used as α-Al heterogeneous nucleation cores. The average grain size and standard deviation of Al-4.5Cu alloy with the addition of 0.02 wt% TiB2 and high cooling rate are 30.5 μm and 15.9, respectively. Compared with the Al-4.5Cu alloy without adding TiB2 particles and at medium cooling rate, the average grain size and standard deviation decreased by 68.1 % and 44.2 %, respectively. It can be seen from the room temperature tensile properties of the alloy after T6 heat treatment, that the yield strength, tensile strength and elongation of the Al-4.5Cu alloys with the addition of 0.02 wt% TiB2 and high cooling rate are 468.3 MPa, 513.9 MPa, and 13.4 %, respectively. Compared with the Al-4.5Cu alloy without adding ceramic particles and at medium cooling rate, the yield strength, tensile strength and elongation increased by 15.6 %, 9.2 % and 25.2 %, respectively.

Optimized EBSD-TEM method for the investigation of Al/Al2O3 interfacial orientation mismatch

The combined electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) method has been commonly applied to investigate material interfaces, from the perspectives of orientation and atomic structure. However, the loose combination is inadequate to capture some slight deviation from the ideal mismatch of interface, which limits an in-depth understanding of the interface. In this study, the combined EBSD-TEM method was systematically optimized and applied to investigate Al-Al2O3 heterogeneous nucleation interface. In this optimized EBSD-TEM method, the cylindrical equidistant projection was employed to illustrate the orientation mismatch relationship instead of the widely used pole figure. Lattice planes and directions from two phases are systematically presented in one figure, which provides a thorough perspective to identify all the potential matching features within the interface, meanwhile ensures a precise guidance for TEM sampling and observation. Such guidance is crucial for interface investigations, thereby this optimized EBSD-TEM method has great potential to be widely applied. Complex interface configurations of Al-Al2O3 interfaces were revealed, including the tilting of Al phase low-indexed planes relative to the interface and the deviations of matched lattice direction pairs between two phases. The complex interface configurations urge further development in the theory of nucleation interface mismatch.

Microstructural behavior of mortars containing thermo-activated crushed demolition residue (TCDR)

The construction industry has been constantly expanding and is, consequently responsible for a high consumption volume of natural raw materials and for generating large amounts of waste. In detriment of this scenario, this research proposes the reuse of Construction and Demolition Waste (CDW), especially that from plaster for making mortars. The residue was thermo-activated at 650 °C for a period of 2h, a heating rate of 10 °C/min, it was crushed in a jaw crusher and passed through an ABNT N° 16 sieve. The mortars were prepared with a (cement:sand) ratio of 1:6 by mass, the sand was partially replaced by the residue in proportions of 0, 10, 20 and 30%, using Ordinary Portland Cement (OPC). Tests were carried out on consistency index, mass density, incorporated air content, isothermal calorimetry, water retention, mass density in the hardened state, flexural strength, compressive strength, water absorption and void index, in addition to testing techniques characterization, such as laser granulometry, pozzolanic activity using the Modified Chapelle method and Lúxan method, X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) as well as Mercury Intrusion Porosimetry (MIP). It was possible to observe that the residue has amorphous phases, through XRD and heterogeneous nucleation of smaller particles, proven by the calorimetry test, contributing to the increase in mechanical strength. The results indicate that the mixture with 30% replacement achieved a greater increase in mechanical strength, lower absorption rates and consequently, a reduction in the distribution of pore sizes.

Excellent combination of strength and ductility in austenitic lightweight steel achieved by warm rolling process

In this study, warm rolling was applied to Fe–28Mn–11Al–1C–5Ni (wt.%) austenitic lightweight steel, which realized the higher dislocation density and finer dislocation-cell structures, achieving a better mechanical properties with ∼2.0 GPa of yield strength and ∼6.8 % of total elongation than cold rolling in the same conditions. In the subsequent partial recrystallization condition, the numerous dislocations and substructures existed in warm rolled steel provide more heterogeneous nucleation sites for grain refinement, resulting in the ultrafine-sized austenite and B2 with the size of 0.36 μm and 0.24 μm, respectively. Combined with grain refinement strengthening, solid solution strengthening, precipitation strengthening, and dislocation strengthening in the unrecrystallized austenite, the present steel shows an ultimate tensile strength of 1734 MPa, a uniform elongation of 21.7 % and a specific tensile strength of 267 MPa g−1 cm3. Such an excellent combination of strength and ductility induced by simple warm rolling and annealing is much better than previously reported for lightweight steels.

Improvement in microstructure and mechanical properties of wire arc additively manufactured 7075 aluminum alloy via adjusting TiC particle addition

7075 aluminum alloys with varying TiC particle additions were fabricated by simultaneously depositing a standard 7075 wire and a TiC treated wire at different wire feed speed ratios. The effects of TiC content on the microstructure and mechanical properties of 7075 alloy were investigated. Results indicated that the addition of TiC particles can effectively refine the grain structure through heterogeneous nucleation, and the grain refinement effect was enhanced with increasing TiC particle content in the range of 0–0.70 wt%. Moreover, TiC particles can restrain the continuous distribution of second phase at grain boundaries. TiC particles tended to cluster at grain boundaries as its content exceeded 0.48 wt%, which adversely affected their beneficial effect on the improvement of mechanical properties. At an optimal TiC content of 0.48 wt%, the tensile strength and elongation in the horizontal direction exhibited remarkable enhancements of 27.2% and 319%, respectively, compared to those without the addition TIC particle.

A biodegradable ZnFe2O4/PLLA electrospun fibers based longitudinal mode piezoelectric membrane for health monitoring

Recently, multifunctional sensors based on piezoelectric active film fabricated with environmental friendly materials is a nascent field which can address the growing concern of electronic waste. Nevertheless, frequently utilized poly(vinylidene fluoride) (PVDF) and poly(L-lactic acid) (PLLA) encounter challenges of limited biocompatibility and weak piezoelectricity with low shear piezoelectric coefficient (d14), respectively. Accordingly, a biodegradable piezoelectric sensor comprising of PLLA nanofiber blended with ZnFe2O4 nanoparticles was developed in this work. The ZnFe2O4 nanoparticles served as heterogeneous nucleation center leading to improved piezoelectric coefficient and output than pure PLLA due to more consistent orientation of CO dipoles. The ZnFe2O4/PLLA film exhibited significant performance improvement featured with 1.7-fold higher longitudinal piezoelectric coefficient (d33 ∼ 6.5 ± 0.3 pm/V), nearly 250 % boosting on the output voltage. The ZnFe2O4/PLLA piezoelectric sensor induced high sensitivity (2–10 N:0.55 V/N; 10–32 N:0.29 V/N) and excellent mechanical stability for 27,000 cycles. The results of the soil burial experiment demonstrate that the film can degrade by over 75 % within 90 days, confirming its excellent biodegradability. Moreover, the ZnFe2O4/PLLA nanofibers based piezoelectric sensor could serve as effective detection evidenced by different output signals of head motion, pulse and artery beating demonstrating its feasible application for health monitoring. Considering the characteristics of straightforward fabrication and readily accessible sustainable materials, the ZnFe2O4/PLLA sensor provides an appealing eco-friendly solution for self-powered flexible personal devices disregarding the need to dispose of electronic waste.

Revealing the heterogeneous nucleation mechanism of Mg17Al12 on impurity Mg2Si particles in commercial AZ31 alloy

Silicon (Si) is an inevitable impurity element in the AZ31 alloy. In this study, the Si impurity was detected mainly as fine Mg2Si particles dispersed widely within the central region of the Mg17Al12 phase. During the solidification process, the Mg2Si particle precipitates at about 565 °C, before the Mg17Al12 phase of 186 °C, potentially acting as the heterogeneous nucleation core for the Mg17Al12 phase. The orientation relationship between Mg2Si and Mg17Al12 was investigated using the edge-to-edge matching model (E2EM) calculations, which showed a misfit of only 0.1 %. This low misfit suggests that Mg2Si can serve as a heterogeneous nucleation site for Mg17Al12. The surface and interface structures of Mg2Si (220) and Mg17Al12 (332) were constructed, and then investigated through the first-principles calculation. The theoretical results indicate that Mg and Al are easily adsorbed on the surface of Mg2Si, with Al showing higher adsorption energy than Mg. Furthermore, the interface between Mg2Si and Mg17Al12 exhibits favorable thermodynamic stability. Combined with experiments and theoretical calculations, it is confirmed that the Mg2Si particles, formed due to the Si impurity, provide effective heterogeneous nucleation sites for the Mg17Al12 phase.

Silk sericin-coated polyamide thin-film composite membranes to simultaneously improve anti-scaling properties, long-term storage, and waste-to-resource recovery

A polyamide thin-film composite (PA-TFC) membrane, which is one of the widely used for desalination and water softening processes, features a lot of carboxyl groups inevitably formed by hydrolysis of unreacted acyl chlorides after interfacial polymerization. However, since carboxyl groups interact with multivalent cations and thereby cause membrane scaling, it is desirable to reduce the density of carboxyl groups on the membrane surface. In this regard, silk sericin (SS) can be an excellent alternative to modifying the surface characteristics to mitigate scaling because it has various hydrophilic amino acids with a much lower density of carboxyl groups per unit mass. Given the properties, we prepared anti-scaling TFC membranes by coating SS on the PA active layer. According to the result, the SS-PA-TFC (16.4% decrease) significantly reduced the flux decline to half of the PA-TFC (36.7% decrease) during the 48-h scaling test under the condition for heterogeneous gypsum crystal nucleation. More importantly, the comparison of operation duration until cleaning obviously revealed the anti-scaling properties of the SS-PA-TFC, which was evidenced by about 7.5 times longer duration than the PA-TFC. Furthermore, the cyclic scaling test in 19 mM CaSO4 showed that the SS-PA-TFC (3.6%) could decrease the irreversible fouling to about one-fifth of the PA-TFC (15.9%). This outstanding anti-scaling performance of the SS-PA-TFC stemmed from the less negatively charged (‐40.8 and ‐28.1 mV for the PA-TFC and SS-PA-TFC, respectively) and much more hydrophilic surface (52.2° and 18.2° for the contact angles of the PA-TFC and SS-PA-TFC, respectively). Suprisingly, the above-mentioned anti-scaling properties of the SS-PA-TFC membrane were achieved without the trade-off between water flux and salt rejection thanks to a very thin SS coating layer (ca. 16 nm). Apart from the anti-scaling properties, SS coating also improved long-term storage and waste-to-resource recovery.

Microstructure and mechanical property improvement of concurrent wire-powder feeding laser melting deposition Ti-6Al-4V via TiC addition

Wire-feed laser metal deposition (LMD-W) offers a high deposition rate and low cost, making it an effective solution for reducing costs and enhancing efficiency in manufacturing large-scale titanium aerospace components. Currently, the material used for LMD-W is typically a single alloy wire, which limits the flexibility and functionality of manufacturing composite materials. This work employed a novel concurrent wire-powder feeding laser metal deposition (LMD-WP) process to manufacture TiC/Ti-6Al-4V composite. In the LMD-WP method, Ti-6Al-4V wire was fed laterally, while TiC particles were delivered coaxially. Only 1.0 wt% TiC particles were added to prevent excessive TiC, which could cause stress concentration and increase crack sensitivity. The microstructure and mechanical properties of Ti-6Al-4V alloy and TiC/Ti-6Al-4V composite were investigated. The results indicate that with coaxial TiC particle addition, the α-Ti in TiC/Ti-6Al-4V is noticeably refined. Additionally, in situ TiC acts as heterogeneous nucleation sites, restricting α-Ti growth and reducing its aspect ratio. Furthermore, TiC particles weakened the α-Ti texture in the (0001) and (11–20) directions. Moreover, adding TiC particles significantly enhanced tensile strength, with the yield strength reaching 950 MPa and the ultimate tensile strength reaching 1048 MPa. Compared to Ti-6Al-4V alloy fabricated by LMD-W, this represents an increase of 11.25% and 10.72%, respectively. The improvement in tensile properties is principally ascribed to grain boundary strengthening, Orowan strengthening and dislocation density strengthening. This work introduces an innovative approach and abundant data for the additive manufacturing of TiC/Ti-6Al-4V composite with high efficiency and low cost.

Effect of N on microstructure, nucleation mechanism and mechanical performance of (Ti, Nb) C particles in Fe-based composite coating via plasma spray welding

Compared with the coating of Ti-Nb-C system, the coating of Ti-Nb-C-N system shows better mechanical properties, especially wear resistance. Therefore, this investigation was focus on the in-situ (Ti, Nb) C reinforced Fe-based composite coatings (D1 composite coatings) and in-situ (Ti, Nb) (C, N) reinforced Fe-based composite coatings (D2 composite coatings) which were created on high strength steel via plasma spray welding (PSW) technology in the environment with nitrogen and without nitrogen, respectively. The two coatings were compared to explore nucleation mechanism of nitrogen on (Ti, Nb) C particles, grain size, particle morphology and the influence on the mechanical performance of coatings. The findings showed that the changes in the typical microstructure morphology and the shape of the reinforced particles of the two coatings were not obvious. However, the heterogeneous nucleation sites of (Ti, Nb) C were provided by introducing nitrogen. In addition, the introduction of nitrogen could refine the grains of D1 composite coatings. As a result, the average grain size of D1 composite coatings decreased by an order of magnitude, and the crystal orientation of the grains in the composite coatings showed better isotropy. The average microhardness of D2 composite coatings was 967.52 HV1, which was 1.5 times of the average microhardness of D1 composite coatings. The wear loss of D2 composite coatings was 0.4 mg, which was only half of that of D1 composite coatings (0.8 mg).

Understanding condensation halo growth on superhydrophobic surfaces: Insights from a vapor diffusive model

Anti-icing technologies are vital across various sectors, from transportation to energy systems. In this study, we investigate the formation of condensation halos during the process of condensation–freezing on superhydrophobic surfaces. Experimental tests were conducted on metallic nanostructured superhydrophobic surfaces, where droplet icing was induced and observed under controlled conditions. The formation of condensation halos, characterized by the sudden appearance and subsequent vanishing of microdroplets around the freezing droplets, was captured and analyzed. A vapor diffusive model coupled with heterogeneous nucleation theory was developed to understand and quantify the growth of condensation halos. The model considers vapor diffusion around the icing droplet and the critical vapor pressure required for nucleation. Experimental observations and theoretical predictions demonstrated a strong dependence of condensation halo size on the icing droplet radius. The study sheds light on the mechanisms underlying condensation halo formation and provides insights into the intricate interplay between droplet size, surface properties, and environmental conditions in condensation–freezing phenomena, offering valuable perspectives for the development of effective anti-icing strategies.

Understanding heterogeneous nucleation and predicting grain size in wire and arc additive manufacturing of steels with inoculation

Understanding heterogeneous nucleation and predicting grain size in wire and arc additive manufacturing of steels with inoculation

Atomic-scale heterointerfacial engineering of multilayered structures in Fe-Cr-based alloys revealed through LRLM model and its modified model

Two Fe-Cr-based alloy foils, denoted as Y2 and MY1 samples, were prepared, as well as transmission electron microscope (TEM) was used to investigate the atomic matching and orientation relationships (ORs) across the interfaces in these samples. From the analyses of the interfaces, the ORs and atomic matching modes between adjacent phases are revealed. Furthermore, the reconstructed multilayer models for each interface have been established on the basis of the ORs, and it is found that the formation of stable interfaces is conductive to the nucleated phases nucleating on the surfaces of the substrates. As for the OR verification, parallel ORs are verified effective through long-range lattice matching (LRLM) model, while non-parallel OR is verified through modified LRLM model. Finally, the sequential atomic heterogeneous nucleation behaviors of TiN and δ-Fe originated from Mg- /Y-bearing oxides have been reconstructed.

The role of symmetric tilt grain boundaries on the precipitation of hydrides in zirconium: A molecular dynamics study

Zirconium (Zr) alloys are widely used as structural materials in the core of nuclear reactors. However, the absorption of hydrogen by these alloys during the reactor operation may lead to the precipitation of hydrides. Such hydrides have considerable effects on the microstructure and mechanical properties of the alloys, thus significantly impacting their overall performance. In this work, we investigate the behavior of hydrogen in the presence of symmetric tilt grain boundaries in Zr using molecular dynamics simulations. To systematically explore the conditions for the formation of hydrides, we consider hydrogen concentration levels of up to 50 at.%. We find that hydrogen concentrations of 30 at.% or lower are below the threshold for the precipitation of hydrides, while fcc coordinated hydrides precipitate at 50 at.%, which is very close to the solubility limit of hydrogen in Zr at 800 K. We find that the grain boundaries (GBs) play a pivotal role in the behavior of hydrogen, as well as the formation of hydrides in Zr systems. In most cases, large amounts of hydrogen are found to accumulate at GBs. However, both homogeneous and heterogeneous nucleation are observed during the formation of hydrides at the grain interiors and GBs, respectively. Nonetheless, in some cases the GB inhibit the formation of hydrides.

Microstructure evolution and property regulation of CoCrNiNbx laser cladding coatings

The influence of different Nb on the microstructure evolution, properties of the CoCrNi laser cladding coatings was investigated. With the increase of Nb addition, the eutectic structures showed a transition from planar crystals to cellular crystals to dendritic crystals. Besides, the eutectic lamellae gradually became dense. A large amount of Ni3Nb-HCP structure precipitates were precipitated in the coatings with excessive Nb. The introduction of Nb brought about an increase in heterogeneous nucleation cores, which in turn significantly refined the grain size in the secondary remelting zone of the cladding coating. As the Nb content increased, the hardness of coatings gradually increased, but both wear resistance and corrosion resistance showed a trend of first increasing and then decreasing.