In order to improve the homogeneity of spherical Fe-rich particles within the Cu-rich matrix, the Cu95Fe5 (wt%) immiscible composite coating has been produced by the combination of mechanical ...alloying and laser cladding. The results show that the milled composite powder presents a polygonal morphology and is mainly composed of face-centered-cubic (fcc)-Cu solid solution. The demixing or delimitation is eliminated in the immiscible composite coating produced by laser cladding and large amounts of spherical α-Fe particles are dispersed within the ε-Cu matrix as a result of liquid phase separation (LPS). The size of the Fe-rich particles measured is in radius of ∼1.5 μm, which is much smaller than the calculated critical radius (∼2.3 μm), confirming that the α-Fe particles containing a supersaturated Cu are driven by the dominant mechanism of Marangoni motion. Compared to Brass, the immiscible composite coating exhibits the improved homogeneous microhardness (153HV0.2) and higher corrosion resistance, as well as a saturated magnetization of ∼9.19 emu/g and low coercivity of ∼9.25 Oe.
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•Homogeneous immiscible coating is produced by mechanical alloying and laser cladding.•Many α-Fe particles with a diameter of ∼3 μm are dispersed within the ε-Cu matrix.•Immiscible coating has higher microhardness and corrosion resistance than Brass.•Immiscible coating exhibits a saturated magnetization of ∼9.19 emu/g.•Immiscible coating exhibits a low coercivity of ∼9.25 Oe.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Metallurgical defects significantly affect the performance of materials fabricated by selective laser melting (SLM), becoming a bottleneck problem in the application of laser 3D printing technology. ...To investigate the effect of metallurgical defects on the magnetic properties of SLM NiFeMo permalloy. An in-depth characterization of the microstructure and phase composition of SLM-fabricated NiFeMo permalloy samples were carried out. Soft magnetic DC BH hysteresis loop tester was used to assess the magnetic properties. Defect voxel data of as-built samples were obtained using X-ray microcomputed tomography (XCT). The results show that the micro-defects of SLM NiFeMo alloy are mainly composed of lack of fusion, pores, etc., and the phase composition of NiFeMo is mainly γ- (Ni, Fe) solid solution. With the increase of laser volume energy density, the Bs and μm of the material increase, while the Hc and Pu decreases. The equivalent diameter of the defects shows a positive correlation with the coercivity (Hc) and a negative correlation with the saturation magnetic induction (Bs) of NiFeMo permalloy.
•The microstructural features, the evolution of defect size and morphology were analyzed and described in detail.•Defect data information in SLM-fabricated permalloy was extracted and quantified using XCT.•Permalloy samples with relatively good magnetic properties were obtained by adjusting the process conditions.•Constructed and validated an approximate relational model describing the correlation of defects and magnetic properties.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The NiCrMoAl/WC composite coatings with different contents of WC particles were deposited on P550 steel by laser cladding. The microstructure and magnetic properties of the coatings were ...characterized by SEM, EDS, XRD and VSM. The magnetism of phases was calculated by the first-principles based on the density functional theory. The results show that the coatings are mainly composed of γ-Ni, WC, W2C, Ni2W4C, Ni3Mo3C, Mo2C and Al4C3. The relative permeability of the coatings increases from 1.002 to 1.080 with the increase of WC percentage from 24 wt% to 60 wt%. The phases of WC, W2C, Ni2W4C and Al4C3 are non-magnetic, Ni3Mo3C and Mo2C are weakly magnetic according to the calculations. The weak magnetism of Ni3Mo3C originates mainly from the strongly correlated interaction of 3d electrons in Ni atoms, whereas that of Mo2C originates mainly from the d-state electrons of Mo atoms. The weak magnetism of the coatings (WC ≥ 48 wt%)is related to the metallurgy behaviors of WC particles. The C elements resulting from the decomposition of WC particles can be diffused into the Ni-based alloy, thus resulting in the formation of weakly magnetic phases in the cladding layer, such as Ni3Mo3C and Mo2C.
•The magnetism of NiCrMoAl/WC coating.•Magnetic calculation by the first-principle.•Magnetism and metallurgical behavior of WC.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The influence of Mn additions on the microstructure and magnetic properties of FeNiCr/60%WC composite coatings produced by laser cladding was investigated. The microstructure of FeNiCr/60%WC coatings ...was characterized using SEM, TEM and XRD. The magnetic properties of the composite coatings were examined by a vibrating sample magnetometer (VSM). The valence electron structure and magnetic moments of Fe3W3C and Fe-based solid solution were calculated according to the empirical electron theory (EET) of solids and molecules. The results showed that FeNiCr/60%WC composite coatings had a high metallurgical quality, and that Mn can stabilize the austenite region and promote the formation of Cr0.19Fe0.7Ni0.11. The relative permeability decreased significantly with increasing the addition of Mn, indicating that Mn had the potential to improve the non-magnetic properties of the composite coatings. EET results revealed that Fe3W3C was a weakly ferromagnetic phase with a magnetic moment of 0.9018, which appeared to be the main factor affecting the non-magnetic properties of the coatings. In addition, given a constant amount of Ni in the Fe-Ni-Cr alloy, the average magnetic moment of the alloy decreased with increasing Mn.
•The FeNiCr/60%WC coatings with different Mn additions were fabricated by laser cladding.•Nonmagnetic properties of laser clad FeNiCr/60%WC coatings were improved by Mn additions.•The magnetic mechanism of FeNiCr/60%WC coatings with different Mn additions was investigated.•The main factor affecting the non-magnetic properties of FeNiCr/60%WC coatings was clarified.
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•High-performance Fe-based coatings were fabricated on the surface of U75V rails by a diode laser.•A rolling contact fatigue test was proposed based on the Hertz contact ...theory.•Evaluation of wheel-rail rolling contact dynamics based on 3D FEM.•The high-performance Fe-based coating significantly improved the RCF and wear resistance of U75V rails.
The microstructures of the Fe-based alloy laser cladding layer were characterized by optical microscope, scanning electron microscope and X-ray diffractometer. The load-bearing performance was evaluated and compared with that of the U75V rail. 3D finite element modelling was performed using the ANSYS software. It is found that the phases of the coating are α-Fe, Fe-Cr, Ni-Cr-Fe and Fe2B, Fe3Si precipitates. The average microhardness of the coating can reach HV455.2, which is higher than that of the heat affected zone (HAZ) and the substrate. The coating can effectively reduce the wear and rolling contact fatigue of heavy-haul rail.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A self-assembled Cu-Fe-Ni-Cr-Si immiscible composite with a bilayer structure was produced by laser induction hybrid cladding (LIHC) as a result of liquid phase separation (LPS). The microstructure ...exhibited by large amounts of ferromagnetic (FM) Fe3Si particles dispersed within the ε-Cu matrix in the upper layer, and many ε-Cu particles embedded within the FM Fe3Si matrix in the lower layer. The microhardness values of the Fe3Si matrix lower layer (758HV0.2) and ε-Cu matrix upper layer (248HV0.2) were ∼7.3 and ∼2.4 times higher than that of pure copper by LIHC, respectively, indicating that the immiscible composite exhibited strongly inhomogeneous characteristics consistent with a “bilayer structure”. Moreover, the immiscible composite showed a high saturation magnetization of 96.2 emu/g and a low coercivity of 7.24 Oe due to the formation of FM Fe3Si with micro- and nanoscaled structures.
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•Composite consists of Cup embedded into Fe3Si matrix and Fep dispersed in ε-Cu matrix.•Immiscible composite exhibits a “bilayer microhardness”.•Immiscible composite has high saturation magnetization (96.2 emu/g).•Immiscible composite exhibits a low coercivity (7.24 Oe).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The main purpose of this research was to investigate the effect of microarc oxidation (MAO) and excimer laser processing on the corrosion resistance of Zr–1Nb alloy in service environment. The ...pre-oxide film was fabricated on the surface of Zr–1Nb cladding tubes by MAO processing, and then subjected to KrF excimer laser irradiation. The surface morphology of the pre-oxide film was observed using a scanning electron microscope; phase compositions and quantities were determined using an X-ray diffraction; surface roughness was determined using a profilometer; and thermal expansion coefficient was measured using a dilatometer. Autoclave experiments were conducted for 94 days in an aqueous condition of 360 °C under 18.6 MPa in 0.01 mol/L LiOH solutions. The results showed that MAO + laser treatment resulted in a significant increase in the corrosion resistance of Zr–1Nb cladding tubes at high temperatures, because laser melting and etching could lead to a reduction in surface roughness and an increase in compactness of the pre-oxide film, and laser processing could promote the transformation of m-ZrO2 phase to t-ZrO2 phase. The best corrosion resistance was obtained when the pulse energy was 500 mJ, scanning speed was 0.13 mm/s, and pulse number was 2400.
•Pre-oxide film was fabricated on Zr–1Nb cladding tube by MAO+ excimer laser processing.•Excimer laser processing induced the transformation of m-ZrO2 to t-ZrO2.•The Rietveld quantitative analysis of the pre-oxide film was made.•We investigated the high temperature corrosion and corrosion mechanism of the oxide film.•The parameters of MAO+ excimer laser processing were optimized.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Metal–matrix composite (MMC) coatings were deposited by laser cladding technique with direct injection of WC–FeNiCr powder onto N1310 nonmagnetic steel matrix. Laser cladding was conducted using a ...Trumpf6000 CO2 laser. The morphology of WC–FeNiCr MMC coatings was characterized using scanning electron microscopy (SEM). Magnetic properties of WC–FeNiCr MMC coatings were examined by vibrating sample magnetometer (VSM) at room temperature. The influence of laser cladding process on the magnetic properties of coatings was investigated. It was found that the content of tungsten carbide and laser power have significant effect on the magnetic properties of composite coatings. The evolution of phase constitution at different laser power was identified by X-ray diffraction (XRD). The presence of an austenitic γ-(Fe, Ni), Cr0.19Fe0.7Ni0.11, Fe3W3C, WC and W2C phases were confirmed by the XRD analysis in the laser clad layer.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The effect of Si addition on phase separation and soft magnetic properties of Cu0.6(FeCrC)0.4100-xSix (x = 3 and 8) immiscible composites produced by laser induction hybrid cladding (LIHC) has been ...investigated. The duplex structure of immiscible composites was composed of many Fe-rich particles dispersed within Cu-rich upper layer and large amounts of Cu-rich particles embedded within Fe-rich lower layer. However, the increasing Si addition not only induced the precipitation of intermetallic compound Cu6.69Si within Cu-rich upper layer, but also increased the area of Fe-rich layer, the size of Fe- and Cu-rich particles, as well as the solubility of Si in Fe- and Cu-rich phases. Moreover, the microhardness of Fe- and Cu-rich layers was increased to 747.3HV0.2 and 302.6HV0.2 in the Cu55.2(FeCrC)36.8Si8 immiscible composite, respectively, which was ∼1.6 and ∼1.8 times higher than that in the Cu58.2(FeCrC)38.8Si3 immiscible composite, due to solid-solution strengthening and dispersion strengthening. Compared to the Cu58.2(FeCrC)38.8Si3 immiscible composite, the Cu55.2(FeCrC)36.8Si8 immiscible composite presented a saturated magnetization of 13.7 emu/g, relatively lower coercivity of 24.9 Oe and higher Curie temperature of larger than 400 K due to appearance of ferromagnetic α-Fe(Si) phase.
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•Increasing Si addition induces the precipitation of intermetallic compound Cu6.69Si.•Increasing Si increases the area of Fe-rich layer, and Fe- and Cu-rich particle size.•Increasing Si addition can increase the microhardness of immiscible composites.•Cu55.2(FeCrC)36.8Si8 composite presented a saturated magnetization (13.7 emu/g).•Cu55.2(FeCrC)36.8Si8 composite presented a low coercivity (24.9 Oe).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
FeNiCr/60%WC coatings were deposited by laser cladding with direct injection of FeNiCr+60%WC powder premixed with different amounts of Mo powder (0–4wt.%) onto the N1310 nonmagnetic steel. The ...morphology was characterized using a scanning electron microscope (SEM), the phase analysis was performed using an X-ray diffractometer (XRD), and the magnetic properties were examined using a vibrating sample magnetometer (VSM). The empirical electron theory (EET) of solids and molecules was used to calculate magnetic moments of Fe3W3C and Ni3Mo3C. The relative permeability of FeNiCr/60%WC composite coatings containing different amounts of Mo ranged from 1.008 to 1.052, which was significantly lower than that without Mo addition (1.104). The relative permeability decreased with increasing Mo content until a minimum was reached, and then increased with further increasing Mo content. Ni3Mo3C phase was formed initially at high Mo addition (≥2.5%) due to the metallurgical reaction between the Mo particles and the Fe-based alloys. Both Ni3Mo3C and Fe3W3C phases were weakly ferromagnetic with a magnetic moment of 0.6816 and 0.9018 respectively, which seemed to be the main factors affecting the non-magnetic properties of the cladding coatings.
•The FeNiCr/60%WC coatings with different Mo additions were fabricated by laser cladding.•The Rietveld quantitative analysis of composite coatings was made.•Nonmagnetic properties of the coatings were improved by Mo additions.•The magnetic properties and microstructure of the coatings with different Mo additions•The magnetic moments of Fe3W3C and Ni3Mo3C phase were calculated by EET.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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