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In this study, AlCoCrFeNi–Cu (Cu-based) and AlCoCrFeNi–Ti (Ti-based) high entropy alloys (HEAs) were fabricated using a direct blown powder technique via laser additive manufacturing on an A301 steel baseplate for aerospace applications. The purpose of this research is to investigate the electrical resistivity and oxidation behavior of the as-built copper (Cu)- and titanium (Ti)-based alloys and to understand the alloying effect, the HEAs core effects and the influence of laser parameters on the physical properties of the alloys.

The as-received AlCoCrFeNiCu and AlCoCrFeNiTi powders were used to fabricate HEA clads on an A301 steel baseplate preheated at 400°C using a 3 kW Rofin Sinar dY044 continuous-wave laser-deposition system fitted with a KUKA robotic arm. The deposits were sectioned using an electric cutting machine and prepared by standard metallographic methods to investigate the electrical and oxidation properties of the alloys.

The results showed that the laser power had the most influence on the physical properties of the alloys. The Ti-based alloy had better resistivity than the Cu-based alloy, whereas the Cu-based alloy had better oxidation residence than the Ti-based alloy which attributed to the compositional alloying effect (Cu, aluminum and nickel) and the orderliness of the lattice, which is significantly associated with the electron transportation; consequently, the more distorted the lattice, the easier the transportation of electrons and the better the properties of the HEAs.

It is evident from the studies that the composition of HEAs and the laser processing parameters are two significant factors that influence the physical properties of laser deposited HEAs for aerospace applications.

The purpose of this study is to investigate the manufacturability of Fe-3Si lattice structures and the resulting mechanical properties. This study could lead to the successful processing of squirrel cage conductors (a lattice structure by design) of an induction motor by additive manufacturing in the future.

The compression behaviour of two lattice structures where struts are arranged in a face-centred cubic position and vertical edges (FCCZ), and struts are placed at body-centred cubic (BCC) positions, prepared by laser powder bed fusion (LPBF), is explored. The experimental investigations are supported by finite element method (FEM) simulations.

The FCCZ lattice structure presents a peak in the stress-strain curve, whereas the BCC lattice structure manifests a plateau. The vertical struts aligned along the compression direction lead to a significant increase in the load-carrying ability of FCCZ lattice structures compared to BCC lattice structures. This results in a peak in the stress-strain curve. However, the BCC lattice structure presents the bending of struts with diagonal struts carrying the major loads with struts near the faceplate receiving the least load. A high concentration of geometrically necessary dislocations (GNDs) near the grain boundaries along cell formation is observed in the microstructure.

To the best of the authors’ knowledge, this is the first study on additive manufacturing of Fe-3Si lattice structures. Currently, there are no investigations in the literature on the manufacturability and mechanical properties of Fe-3Si lattice structures.

This study aims to investigate the chromium (Cr) effects on the microstructural, mechanical and thermal properties of melt-spun Sn-3.5Ag alloy.

Ternary melt-spun Sn-Ag-Cr alloys were investigated using X-ray diffractions, scanning electron microscope, dynamic resonance technique, instron machine, Vickers hardness tester and differential scanning calorimetry.

The results revealed that the Ag₃Sn intermetallic compound (IMC) and ß-Sn have been refined because of the hard inclusions’ (Cr atoms) effects, causing lattice distortion increasing these alloys. The tensile results of Sn_96.4-Ag_3.5-Cr_0.1 alloy showed an improvement in Young’s modulus more than 100 per cent (42.16 GPa), ultimate tensile strength (UTS) by 9.4 per cent (23.9 MPa), compared with the eutectic Sn-Ag alloy due to the high concentration of Ag₃Sn and their uniform distribution. Shortage in the internal friction (Q⁻¹) of about 54 per cent (45.1) and increase in Vickers hardness of about 7.4 per cent (142.1 MPa) were also noted. Hexagonal Ag₃Sn formation led to low toughness values compared to the eutectic Sn-Ag alloy, which may have resulted from the mismatching among hexagonal Ag₃Sn phase with orthorhombic Ag₃Sn and ß-Sn phases. Mechanically, the values of Young’s modulus have been increased, with increasing chromium content, whereas the UTS and toughness values have been decreased. The opposite of this trend appeared in Sn_95.8-Ag_3.5-Cr_0.7 alloy, which may have been due to high lattice distortion (ƹ = 16.5 × 10⁻⁴) compared to the other alloys. Increase in the melting temperature T_m, ΔH, C_p and ΔT was because of Ag₃Sn IMC formation. The low toughness of Sn₉₆-Ag_3.5-Cr_0.5 and Sn_95.8-Ag_3.5-Cr_0.7 (109.56 J/m³ and 35.66 J/m³), relatively high melting temperature Tm (223.22°C and 222.65°C) and low thermal conductivity and thermal diffusivity (32.651 w.m⁻¹.k⁻¹ and 0.314 m²/s) make them undesirable in the soldering process. The high UTS, high E, high thermal conductivity and diffusivity, low creep rate and low electrical resistivity, which have occurred with “0.1 Wt.%” of Cr, make this alloy desirable and reliable for soldering applications and electronic assembly.

This study provides chromium effects on the structure of the eutectic Sn-Ag rapidly solidified by melt-spinning technique. In this paper, the authors compared the elastic modulus of the melt-spun compositions, which have been resulted from the Static method with that have been resulted from the Dynamic method. This paper presents new improvements in mechanical and thermal performance.

Nickel-aluminum bronze (NAB) has been widely used in ship propellers. It is always subjected to local micro-plastic deformation in service environments. This paper aims to study the influence of plastic deformation on the mechanical strength and corrosion resistance of NAB in 3.5 Wt.% NaCl solution.

Scanning electron microscope and X-ray diffraction were used to analyze the microstructure of NAB alloy with different plastic deformations. Mechanical properties of the sample were measured by tensile experiment, and corrosion behavior was studied by electrochemical measurements and the long-term immersion corrosion test.

Results showed that the plastic deformation caused lattice distortion but did not change the microstructure of NAB alloy. Microhardness and yield strength of NAB were significantly improved with the increase of deformation. The lattice distortion accelerated the formation of corrosion product film, which made the deformed alloy show a more positive open-circuit potential and an increased Rp. However, during the long-term immersion corrosion, the corrosion resistance of NAB alloys deteriorated with the increase of plastic deformation. This is because larger plastic deformation brought about higher internal stress in corrosion product film, which resulted in the premature peeling of the film and the loss of its protective effect on the alloy substrate.

Tensile plastic deformations were found to cause a decline in the corrosion resistance of NAB. And the mechanism was clarified from the evolution of corrosion products during the corrosion process.

With excellent mechanic properties and hydrogen embrittlement (HE) resistance, 12Cr2Mo1R(H) steel is suitable to make hot-wall hydrogenation reactors. However, longtime exposure to a harsh environment of high-pressure hydrogen at medium temperature in practical application would still induce severe hydrogen uptake and eventually damage the mechanical properties of the steel. The study aims to evaluate the HE resistance of the steel under different tensile strain rates after hydrogen charging and analyze the hydrogen effect from atomic level.

This research studied the HE properties of 12Cr2Mo1R(H) steel by slow strain rate tests. Meanwhile, the effect of hydrogen on the structures and the mechanical properties of the simplified models of the steel was also investigated by first-principle calculations.

Experimental results showed that after hydrogen pre-charging in this work, hydrogen had little effect on the microstructure of the steel. The elongations and reduction of cross-sectional area of the samples reduced a lot, by contrast, the yield and tensile strengths changed slightly. The 12Cr2Mo1R(H) steel was not very susceptible to HE with a maximum embrittlement index of about 20.00%. First principles calculation results showed that after H dissolution, lattice distortion occurred and interstitial H atoms would preferentially occupy the tetrahedral interstitial site in bcc-Fe crystal and increase the stability of the supercells. With the increase of H atoms added into the simplified model, the steel still possessed a good ductility and toughness at a low hydrogen concentration, while the material would become brittle as the concentration of hydrogen continued to increase.

These finds can provide valuable information for subsequent HE studies on this steel.

The purpose of this study was to clarify the applicable conditions for coatings with different element contents. Surface coating on existed tool material is an effective way to improve the cutting tool properties in extremely adverse machining conditions. These coatings are generally non-metering compounds. Each coating with a certain element ratio has a specific application condition, and the relationship between element contents and performance should be defined.

(Zr, Ti)N hard coatings with different element contents were deposited on cemented carbide. The ball-on-disk method reciprocating sliding wear tests against 40Cr hardened steel were carried out. This paper was focused on analysis of the friction and wear behaviors of these (Zr, Ti)N coatings with different element contents.

The results indicated that atomic ratio of Zr and Ti was the main factor that decided the friction coefficients. The friction coefficient and wear rate showed a gradual downward trend at 10 N with the increase of Zr content. The wear rate was the smallest at the atomic percentage of nitrogen 0.466. If the lattice distortion of the coatings gets too severe, the coatings would have a high wear rate.

The optimal application conditions of the coatings were defined, and this was important for customized design or choice of the coatings under different cutting parameters.

This study aims to investigate the structural, mechanical, thermal and electrical properties of tin–silver–nickel (Sn-Ag-Ni) melt-spun solder alloys. So, it aims to improve the mechanical properties of the eutectic tin–silver (Sn-Ag) such as tensile strength, plasticity and creep resistance by adding different concentrations of Ni content.

Ternary melt-spun Sn-Ag-Ni alloys were investigated using x-ray diffractions, scanning electron microscope, dynamic resonance technique (DRT), Instron machine, Vickers hardness tester and differential scanning calorimetry.

The results revealed that the Ni additions 0.1, 0.3, 0.5, 0.7, 1, 3 and 5 Wt.% to the eutectic Sn-Ag melt-spun solder were added. The “0.3wt.%” of Ni was significantly improved its mechanical properties to efficiently serve under high strain rate applications. Moreover, the uniform distribution of Ag₃Sn intermetallic compound with “0.3wt.%” of Ni offered the potential benefits, such as high strength, good plasticity consequently and good mechanical performance through a lack of dislocations and microvoids. The tensile results showed improvement in 17.63 per cent tensile strength (26 MPa), 21 per cent toughness (1001 J/m³), 22.83 per cent critical shear stress (25.074 MPa) and 11 per cent thermal diffusivity (2.065 × 10⁻⁷ m²/s) when compared with the tensile strength (21.416 MPa), toughness (790 J/m³), critical shear stress (19.348 MPa) and thermal diffusivity (1.487 × 10⁻⁷ m²/s) of the eutectic Sn-Ag. Slight increments have been shown for the melting temperature of Sn_96.2-Ag_3.5-Ni_0.3 (222.62°C) and electrical resistivity to (1.612 × 10⁻⁷ Ω.m). It can be said that the eutectic Sn-Ag solder alloy has been mechanically improved with “0.3wt.%” of Ni to become a suitable alloy for high strain rate applications. The dislocation movement deformation mechanism (n = 4.5) without Ni additions changed to grain boundary sliding deformation mechanism (n = 3.5) with Ni additions. On the other hand, the elastic modulus, creep rate and strain rate sensitivity with “0.3wt.%” of Ni have been decreased. The optimum Ni-doped concentration is “0.7wt.%” of Ni in terms of refined microstructure, electrical resistivity, Young’s Modulus, bulk modulus, shear modulus, thermal diffusivity, maximum shear stress, tensile strength and average creep rate.

This study provides nickel effects on the structural of the eutectic Sn-Ag rapidly solidified by melt-spinning technique. In this paper, the authors have compared the elastic modulus of the melt-spun compositions which has been resulted from the tensile strength tester with these results from the DRT for the first time to best of the authors’ knowledge. This paper presents new improvements in mechanical and electrical performance.

This paper aims to summarise the effects of ZnO nanoparticles (0.1, 0.3, 0.5, 0.7 and 1.0 Wt.%) on the structure, mechanical, electrical and thermal stability of Sn–3.5Ag–0.5Cu (SAC355) solder alloys for high-performance applications.

The phase identification and morphology of the solders were studied using X-ray diffraction and scanning electron microscopy. Thermal parameters were investigated using differential scanning calorimetry. The elastic parameters such as Young's modulus (E) and internal friction (Q⁻¹) were investigated using the dynamic resonance technique, whereas the Vickers hardness (Hv) and creep indentation (n) were examined using a Vickers microhardness tester.

Microstructural analysis revealed that ZnO nanoparticles (NPs) were distributed uniformly throughout the Sn matrix. Furthermore, addition of 0.1, 0.3 and 0.7 Wt.% of ZnO NPs to the eutectic (SAC355) prevented crystallite size reduction, which increased the strength of the solder alloy. Mechanical parameters such as Young's modulus improved significantly at 0.1, 0.3 and 0.7 Wt.% ZnO NP contents compared to the ZnO-free alloy. This variation can be understood by considering the plastic deformation. The Vickers hardness value (Hv) increased to its maximum as the ZnO NP content increased to 0.5. A stress exponent value (n) of approximately two in most composite solder alloys suggested that grain boundary sliding was the dominant mechanism in this system. The electrical resistance (ρ) increased its maximum value at 0.5 Wt.% ZnO NPs content. The addition of ZnO NPs to plain (SAC355) solder alloys increased the melting temperature (T_m) by a few degrees.

Development of eutectic (SAC355) lead-free solder doped with ZnO NPs use for electronic packaging.

The purpose of this paper is to formulate an algorithm for a novel damage‐coupled material law for crystalline polyethylene at finite inelastic strains followed by investigation of the influence of the aggregate representation and material parameters on the material response.

The constitutive equations are developed within the framework of continuum damage mechanics to describe crystal fragmentation caused by atomic debonding of the crystallographic planes. The material is assumed initially isotropic and homogeneous and is represented as an aggregate of randomly oriented crystals with an orthorhombic lattice. For the velocity gradient, an additive decomposition into symmetric and skew‐symmetric components is applied, where the skew‐symmetric part (spin) is decoupled from the lattice shear by means of a damage variable. Structural features such as lattice parameters and orientations, slip systems, and kinematic constraints are incorpo‐rated.

The proposed model is implemented to predict stress‐strain behaviour under uniaxial tension and damage accumulation and texture development at the different stages of deformation. In the numerical examples, the effects of the aggregate size, crystal orientations, and material parameters on the model estimates are analyzed.

The model used herein is a first attempt to analyze the influence of crystal fragmentation caused by the debonding of the crystallographic planes on the predicted mechanical behaviour and texture development of polyethylene prior to failure.

This study aims to review the recent advancements in high entropy alloys (HEAs) called high entropy materials, including high entropy superalloys which are current potential alternatives to nickel superalloys for gas turbine applications. Understandings of the laser surface modification techniques of the HEA are discussed whilst future recommendations and remedies to manufacturing challenges via laser are outlined.

Materials used for high-pressure gas turbine engine applications must be able to withstand severe environmentally induced degradation, mechanical, thermal loads and general extreme conditions caused by hot corrosive gases, high-temperature oxidation and stress. Over the years, Nickel-based superalloys with elevated temperature rupture and creep resistance, excellent lifetime expectancy and solution strengthening L12 and γ´ precipitate used for turbine engine applications. However, the superalloy’s density, low creep strength, poor thermal conductivity, difficulty in machining and low fatigue resistance demands the innovation of new advanced materials.

HEAs is one of the most frequently investigated advanced materials, attributed to their configurational complexity and properties reported to exceed conventional materials. Thus, owing to their characteristic feature of the high entropy effect, several other materials have emerged to become potential solutions for several functional and structural applications in the aerospace industry. In a previous study, research contributions show that defects are associated with conventional manufacturing processes of HEAs; therefore, this study investigates new advances in the laser-based manufacturing and surface modification techniques of HEA.

The AlxCoCrCuFeNi HEA system, particularly the Al0.5CoCrCuFeNi HEA has been extensively studied, attributed to its mechanical and physical properties exceeding that of pure metals for aerospace turbine engine applications and the advances in the fabrication and surface modification processes of the alloy was outlined to show the latest developments focusing only on laser-based manufacturing processing due to its many advantages.

It is evident that high entropy materials are a potential innovative alternative to conventional superalloys for turbine engine applications via laser additive manufacturing.