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The structural, elastic, and thermal characteristics within the 0–30 GPa pressure range of Al3Ni intermetallic compounds were extensively studied using first-principles computational techniques. Using structural optimization, lattice parameters and the variation in volume variation under diverse pressures were determined, and the trends in their structural alteration with pressure were identified. The computed elastic constants validate the mechanical stability of Al3Ni within the applied pressure range and show that its compressive stiffness and shear resistance increase rapidly with increasing pressure. The Cauchy pressure variation implies that the metallic nature of Al3Ni increases gradually with increasing pressure. Moreover, through analysis of Poisson's ratio, the anisotropy factor, and the sound velocity, we ascertained that pressure attenuates the anisotropic attributes of the material, and Al3Ni exhibits more pronounced isotropic characteristics and mechanical homogeneity under high-pressure conditions. The substantial increase in the Debye temperature further suggests that high pressure fortifies the lattice dynamic rigidity of the material. This current research systematically elucidated the stability of Al3Ni under high-pressure conditions and the law of the transformation of it mechanical behavior, providing a theoretical foundation for its application under extreme circumstances. [ABSTRACT FROM AUTHOR]

The structural, elastic, and thermal characteristics within the 0–30 GPa pressure range of Al3Ni intermetallic compounds were extensively studied using first-principles computational techniques. Using structural optimization, lattice parameters and the variation in volume variation under diverse pressures were determined, and the trends in their structural alteration with pressure were identified. The computed elastic constants validate the mechanical stability of Al3Ni within the applied pressure range and show that its compressive stiffness and shear resistance increase rapidly with increasing pressure. The Cauchy pressure variation implies that the metallic nature of Al3Ni increases gradually with increasing pressure. Moreover, through analysis of Poisson’s ratio, the anisotropy factor, and the sound velocity, we ascertained that pressure attenuates the anisotropic attributes of the material, and Al3Ni exhibits more pronounced isotropic characteristics and mechanical homogeneity under high-pressure conditions. The substantial increase in the Debye temperature further suggests that high pressure fortifies the lattice dynamic rigidity of the material. This current research systematically elucidated the stability of Al3Ni under high-pressure conditions and the law of the transformation of it mechanical behavior, providing a theoretical foundation for its application under extreme circumstances.

In this study, the researchers examined the impact of adding different percentages of nickel (0 %, 0.01 %, 0.05 %, 0.1 wt%) to an aluminum-silicon (Al-Si) alloy. Aluminum alloys are widely used in various industries due to their lightweight nature and favorable mechanical properties. The microstructure of the alloy was analyzed using X-ray diffraction (XRD) and scanning electron microscope (SEM) tests.The XRD and SEM analyses revealed that the Al-Si alloy consisted of two phases: α-Al and Si. The introduction of nickel resulted in the detection of an intermetallic compound (IMC) known as Al3Ni. This IMC caused changes in the lattice constant and interatomic spacing (dhkl). The observed distortions and densification in the microstructure were identified as indicators of increased hardness and strength in the alloys. The researchers attribute this enhancement in microstructure properties to the elevated temperature, which facilitated greater diffusion of nickel atoms into the aluminum lattice.

Aluminium and its alloys have a wide range of applications, especially in the automotive sector. Typically, aluminum alloys are utilized in pistons and cylinders of automotive engines. Hence, repeated sliding with low amplitude (fretting) under adverse thermal and mechanical loading conditions dominates the wear of components. In this present work, the effect of solutionizing time on the fretting wear behaviour of Al-Si-Mg-Ni hypoeutectic alloy against alumina ball is investigated under varying normal loads of 5, 10, and 15 N. The fretting wear characteristics in terms of friction coefficient, wear volume and wear scar analyses with the aid of scanning electron microscope and optical profilometry have been systematically conducted. Results showed that with varying solutionizing time, a considerable change in the microstructural aspects of Al-Si-Mg-Ni alloy in the form of Al3Ni and Si precipitation is observed. Moreover, a refinement in the grains is also noticed as the solutionizing time increased from 2 to 10 h. The improved wear resistance is corroborated by the increased hardness arising from the improved intragranular precipitation of Al3Ni and Si. In addition, a reduction in the steady-state coefficient of friction with an increase in the normal load and a concomitant decrease in the wear scar size is also reported. This friction coefficient reduction could be ascribed to the presence of a tribolayer generated between the contacting surfaces for which the formation and coverage are escalated with increasing normal loads. [ABSTRACT FROM AUTHOR]

Low-carbon cobalt-based alloy coatings with high ductility and low thermal fatigue crack propagation rates were prepared using laser cladding (LC) technology. The microstructure of the coatings was characterized using SEM, EBSD, and TEM, while the mechanical properties were tested and analyzed. The CoCrMo alloy primarily consists of γ-Co and a minor amount of ε-Co. The addition of Ni increased the stacking fault energy (SFE), resulting in the retention of γ-Co in the alloy. However, the increase of Al content reduced the SFE, leading to the precipitation of Al 3 Ni intermetallic compound along with a eutectic region with Al 3 Ni, Cr 23 C 6 , and ε-Co. More ε-Co phase appeared after tensile deformation due to the stress-induced transformation induced plasticity (TRIP) effect. Ni addition increased the content of face-centered cubic (fcc) γ-Co, enhancing the coating's ductility by approximately 85 % compared to CoCrMo. With higher Al content, the ε-Co phase increased, and the dispersion of Al 3 Ni improved the coatings' strength. The jagged structure of the eutectic region increased the resistance to thermal fatigue crack propagation, causing the crack propagated along the grain boundary. Optimal mechanical properties were achieved with the addition of 13 wt% Ni and 7 wt% Al, which achieved a 53 % increase in ductility and a 40 % reduction in the thermal fatigue crack propagation rate compared to CoCrMo. • Ni/Al modified CoCrMo alloy fusion coatings exhibit excellent strength and thermal fatigue properties. • The addition of Al element changed the solidification process and products of eutectic organization. • Ni increased the stacking faults energy (SFE) of Co-based alloys, which decreased with the increase of Al content. [ABSTRACT FROM AUTHOR]

Al/Al3Ni and Al/nano‐ZrO2 mono and Al/Al3Ni/ZrO2 hybrid composites were produced by one‐ and four‐pass friction stir processing (FSP). Then, the microstructure, hardness, and wear performance of the surface composites were evaluated. Results showed that the incorporation of Ni particles into the Al surface and their in situ reaction with the substrate resulted in the development of Al3Ni particles in the stir zone. The formation mechanism of these particles was deeply studied from both thermodynamics and kinetics aspects. Similarly, the four‐pass FSP led to the distribution of ZrO2 nanoparticles and the formation of Al/ZrO2 composites. With the addition of both Ni and ZrO2 particles, a hybrid Al/Al3Ni/ZrO2 composite was produced. This caused a 60% improvement in hardness and a 35% improvement in wear resistance of Al substrate. In the case of monolithic composites, both abrasion and adhesion were responsible for the material removal during the wear test, whereas adhesion was specified as the dominant wear mechanism in the hybrid composite. [ABSTRACT FROM AUTHOR]

Corrosion behaviors of Al-15%Mg2Si-1%Ni alloy in 3.5% NaCl solution were studied by characterizing the corrosion morphologies of Al3Ni, Mg2Si, and Al phases. The results show that there are two galvanic coupling systems (Al/Al3Ni and Al/Mg2Si) in Al-15%Mg2Si-1%Ni alloy. In the Al/Al3Ni coupling system, the intermetallic Al3Ni phase (nobler than the Al matrix) acts as the cathode throughout the corrosion process. For the Al/Mg2Si coupling system, electrochemical polarity conversion occurs between the Al matrix and the Mg2Si phase. The corrosion pits around the Al3Ni and Mg2Si are connected to form long corrosion channels, which accelerate corrosion of the Al-Mg2Si-Ni alloys.

Abstract Modification of a coarse B2 phase and realization of hierarchical multi-phase microstructures were achieved in an Al 0.5 CrFeCoNi complex concentrated alloy (CCA) using high-temperature severe plastic deformation (HTSPD). Under HTSPD conditions, a thermodynamically stable B2 phase dissolved, while a thermodynamically unstable coarse Al 3 Ni phase formed. Al supersaturation in the matrix after HTSPD led to the formation of fine B2 precipitates during the subsequent aging treatment. The combination of Al 3 Ni for enhanced work hardening and fine B2 precipitates for strength resulted in excellent strength-ductility of 1400 MPa and 20%. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

The axial fan blades used in underground mines are usually manufactured in AlSi12CuMgNi alloy (EN AC 48000). They must have a high mechanical strength to withstand the stresses resulting from the rotation speed of the rotor and a high resistance to erosive wear caused by suspended particles from underground mining and transport operations. The aim of this paper is to determine the most suitable thermal treatment to simultaneously improve their mechanical strength and erosive wear resistance. To this end, two solution treatments at 525 °C with cooling in water were analysed, as well as several ageing times at 170 °C. The crystalline phases present in the as-cast state were quantified by X-ray diffraction following quenching and different ageing processes. Furthermore, erosion wear resistance was measured by means of compressed air blasting with corundum particles according to ASTM G76 (2004). The highest wear resistance was obtained in the as-cast state using gravity die casting, with the presence of Al4Cu2Mg8Si7 and Al3CuNi. This wear resistance was higher than that obtained after the ageing treatment. However, a trade-off between mechanical strength and wear resistance was observed after 12 h ageing, where the hardness obtained exceeded 160 HV and the wear resistance became similar to that obtained in the as-cast state.

Aluminum-silicon (AlSi) composite reinforced with 20 wt% Ni particulates was produced by hot pressing and characterized using nanoindentation. Energy dispersive spectrometry and X-ray diffraction analyses showed that Al3Ni intermetallic was formed in the interface between Ni particulates and AlSi matrix. Chemical composition, hardness, and elastic modulus were studied along the interface from inner (near Ni) to outer (near AlSi) regions. A uniform composition was found throughout the interface, having 805.6 HV hardness and elastic modulus of 185.4 GPa. Interface properties have a crucial influence on the composite performance and their assessment is of paramount importance on composite properties estimation using predictive models. [ABSTRACT FROM PUBLISHER]

A new process is proposed to fabricate an intermetallic compound-reinforced aluminum alloy matrix composite using the reaction between porous nickel and molten aluminum alloy. The intermetallic compound-reinforced aluminum alloy composite was manufactured with the infiltration process method. Porous nickel reacted with the molten aluminum alloy at 973 K, and the intermetallic compound of Al3Ni was generated on the surface of the porous nickel. The generated intermetallic compound Al3Ni is delaminated due to different thermal expansion coefficient with nickel and moves in the direction of aluminum matrix. The effects of processing variables such as specific surface area of porous nickel, holding time after infiltrated molten aluminum alloy, and cooling rate on the formation and dispersion behavior of Al3Ni were investigated. [ABSTRACT FROM AUTHOR]

Abstract: This work investigated the refinement of Al3Ni phase in Ni-7050 composite, which was prepared by the melting reaction with two different components, 5% and 10% Ni added in 7050 aluminium alloy. Hardness tests, metallographic observation, SEM and DSC were used to analyze the structures and performances. The results show that the hardness of the two composites was obviously increased to 1918 and 2364 MPa after T6 aging. Fracture analysis shows that the fracture mechanism was mainly Al3Ni brittle fracture and interfaces debond. Experiments were designed to investigate the influences of annealing/rolling treatment on structures and properties of the composites. The results indicated: (1) Long time annealing treatment could induce refinement and spheroidization of the Al3Ni phase. With the annealing time prolonged, the hardness first increased and then decreased. (2) After multi-step hot/cold rolling, the microscopic structure of composites showed that the size of Al3Ni phase changed progressively, Al3Ni phase was smashed and transformed from original long slab to nearly isometric particles. [Copyright &y& Elsevier]

Abstract: Ultrafine-grained in situ synthesized Al3Ni particulate-reinforced composites were fabricated by friction stir processing (FSP) introduced Ni powder into the stirred zone of 1100-H14 aluminum alloy. The microstructures and the compositions of the composites were analyzed by SEM, EDS and XRD. The microhardness and ultimate tensile strength (UTS) were measured. The XRD and EDS analyses showed that the Al–Ni in situ synthesizing product was Al3Ni. When the specimen was stirred 2 passes, the formed Al3Ni was tiny to be detected. Al3Ni subsequently became apparent when stirring 4 and 6 passes and the fine Al3Ni particles were dispersed homogeneously in the composites, which caused significant increases of the microhardness and UTS of the composites. The effective Gibbs free energy change of formation model was proposed to predict the Al–Ni compound formation at solid-state interface and the calculation combined with kinetic factors showed that Al3Ni was the product, which supports the experimental observation. [Copyright &y& Elsevier]

The self-propagating foaming process of porous Al-Ni intermetallics was investigated. Aluminum and nickel powders were blended, and titanium and boron carbide powders were added as reactive exothermic agents. The blended powder was extruded to make a rod-shape precursor. Only one end of the rod precursor was heated to ignite the reaction. The reaction propagated spontaneously throughout the precursor. Pore formation took place at the same time as the reaction occurred. Adding the exothermic agent was effective to increase the porosity. Preheating the precursor before the ignition was also very effective to produce porous Al-Ni intermetallics with high porosity. [ABSTRACT FROM AUTHOR]

The Al–Al 3 Ni–Sn composite was developed using a powder compassion and sintering metallurgical processing route. Microstructures of the sintered samples revealed the combination of a globular, chain-like and elliptic (raindrop) Al 3 Ni phases. The differential scanning calorimetry (DSC) analysis confirmed the high temperature stability of the composite. After heat treatment conducted at 500 °C, the Al 3 Ni chain-like phase in the matrix transformed to raindrop particles. The presence of the Al 3 Ni intermetallic compound had a positive effect on the hardness since the Al–Al 3 Ni–Sn composite was harder in comparison to the A356 aluminium alloy. Microstructures were analysed using the LEO 1525 field-emission scanning electron microscope (FE-SEM). The XPS scanned spectra of the A356-Ni-Sn alloy revealed the Al2p, Si2p, C1s, Sn3d5, O1s, Ni2p3 and Mg1s intensity peaks. • MMC with Al 3 Ni was developed from A356, Ni (5 wt %) and Sn (3 wt %) powders. • Sintered samples revealed a globular, chain-like and elliptic Al 3 Ni phase. • The alloy was stable at high temperature. • XPS confirmed the Al2p, Si2p, C1s, Sn3d5, O1s, Ni2p3 and Mg1s peaks. [ABSTRACT FROM AUTHOR]

A powder blend of Ni particles embedded in Al flakes obtained after high energy ball milling was used to reinforce an Al Mg alloy using friction stir processing (FSP). The mechanical activation provided by both ball milling and FSP resulted in the in-situ formation of nickel aluminides during FSP, which was distributed throughout the nugget zone. The average grain size after FSP was 8.3 μm. High dislocation density was observed in the vicinity of the reinforcements. The yield and ultimate tensile strengths of the composite improved by 123% and 78% respectively. The tensile elongation of the composite was 23% and the base material, 32%. The toughness of the composite improved by 42%. At elevated temperatures (200 °C and 300 °C), the composite exhibited a decrease in strength but an increase in ductility with increasing temperature. • Al5052 alloy was reinforced with a powder blend of Ni particles and Al flakes using friction stir processing (FSP). • Ni reacted with Al during FSP to form a core-shell type structure with Ni 3 Al as the shell and Ni as the core. • The shell then fragmented into much finer sizes during FSP and formed Al 3 Ni with further reaction with Al. • Improvement in the mechanical properties was observed, especially, toughness. • A transition from strain hardening to strain softening was observed at elevated temperatures. [ABSTRACT FROM AUTHOR]

• In the Al-Al 3 Ni coupling system, the intermetallic Al 3 Ni phase acts as cathode. • The polarity conversion of Al and primary Mg 2 Si lags behind that of Al and eutectic Mg 2 Si. • The corrosion pits around the Al 3 Ni and Mg 2 Si are connected to form long corrosion channels. Corrosion behaviors of Al-15%Mg 2 Si-1%Ni alloy in 3.5% NaCl solution were studied by characterizing the corrosion morphologies of Al 3 Ni, Mg 2 Si, and Al phases. The results show that there are two galvanic coupling systems (Al/Al 3 Ni and Al/Mg 2 Si) in Al-15%Mg 2 Si-1%Ni alloy. In the Al/Al 3 Ni coupling system, the intermetallic Al 3 Ni phase (nobler than the Al matrix) acts as the cathode throughout the corrosion process. For the Al/Mg 2 Si coupling system, electrochemical polarity conversion occurs between the Al matrix and the Mg 2 Si phase. The corrosion pits around the Al 3 Ni and Mg 2 Si are connected to form long corrosion channels, which accelerate corrosion of the Al-Mg 2 Si-Ni alloys. [ABSTRACT FROM AUTHOR]

The axial fan blades used in underground mines are usually manufactured in AlSi12CuMgNi alloy (EN AC 48000). They must have a high mechanical strength to withstand the stresses resulting from the rotation speed of the rotor and a high resistance to erosive wear caused by suspended particles from underground mining and transport operations. The aim of this paper is to determine the most suitable thermal treatment to simultaneously improve their mechanical strength and erosive wear resistance. To this end, two solution treatments at 525 °C with cooling in water were analysed, as well as several ageing times at 170 °C. The crystalline phases present in the as-cast state were quantified by X-ray diffraction following quenching and different ageing processes. Furthermore, erosion wear resistance was measured by means of compressed air blasting with corundum particles according to ASTM G76 (2004). The highest wear resistance was obtained in the as-cast state using gravity die casting, with the presence of Al4Cu2Mg8Si7 and Al3CuNi. This wear resistance was higher than that obtained after the ageing treatment. However, a trade-off between mechanical strength and wear resistance was observed after 12 h ageing, where the hardness obtained exceeded 160 HV and the wear resistance became similar to that obtained in the as-cast state. [ABSTRACT FROM AUTHOR]