Phase composition and structure of multilayered coatings of Ni-Al system (original) (raw)
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The fine structure of coatings on the basis Ni-Al formed by the magnetron method
2014
Phase composition, fine structure and surface morphology of intermetallic coatings are investigated by X-ray analysis and TEM. It is shown that Ni 3 Al is the main phase of the intermetallic coating for all the investigated samples. There is a Ni-Al phase in the samples of the first type. Three types of grains, differing in size, are discovered in the structure of nanocrystalline coatings: dislocation free, dislocation, and fragmented. The internal stresses, obtained by TEM and X-ray analysis, have close values.
IOP Conference Series: Materials Science and Engineering, 2020
In the present study the thin NiAl intermetallic foils formed on different types of substrates by magnetron sputtering technique were investigated. To provide the deposition of intermetallic NiAl compound in one step without additional heat treatment the composite targets assembled from parts of Al and Al plates were used. The structure of formed thin NiAl coatings was studied using scanning electron microscopy and X-ray diffraction analysis. Mechanical properties were assessed by nanohardness indentation and wear testing of deposited coatings. During sputtering the distance from the target to the substrates varied from 60 to 100 mm to estimate the effect of this parameter on structure and properties of the coatings. The results revealed that thin coatings sputtered at the closer distance from the target to the substrates had the higher hardness about 11 GPa and exhibited the high level of wear properties.
XRD and TEM Heating of Large Period Ni/Al Multilayer Coatings
Acta Physica Polonica A, 2016
The Ni/Al multilayer coating of λ ≈ 100 nm was deposited onto (001)-oriented monocrystalline silicon substrate using double target magnetron sputtering system equipped with rotating sample holder. The thicknesses of alternating layers were adjusted in the way to preserve the chemical composition ratio close to 50%Al:50%Ni (at.%). The in situ X-ray diffraction and in situ transmission electron microscopy heating experiments were carried out at relatively low heating rates (20 • C/min) in order to study the phase transformation sequence. The investigations revealed that the reaction between Ni and Al multilayers starts at ≈200 • C with precipitation of Al3Ni phase, while above 300 • C dominates precipitation of Ni3Al and NiAl intermetallic phases. Both the X-ray and electron diffractions acquired at 450 • C confirmed presence of the Ni3Al and NiAl intermetallics, but the former pointed at still lasting traces of Ni(Al) solid solution.
Structure Characterization of Ni/Al2O3 Composite Coatings Prepared by Electrodeposition
Solid State Phenomena, 2010
In the present study, the electrodeposition of composites consisted of metal matrix (nickel) and inert particles (hard nano-sized Al 2 O 3 oxide) has been carried out in a Watt's type bath of pH 4, at room temperature in a system with the steel rotating disk electrode. The influence of dispersed Al 2 O 3 powder on structure characteristics (morphology, phase composition, texture, residual stresses) of Ni/Al 2 O 3 coatings has been investigated. The crystallographic texture of Ni and Ni/Al 2 O 3 coatings deposited on the steel substrates was analyzed by XRD technique based on the back-reflection pole figures. The "sin 2 ψ" X-ray diffraction method was used to determine the residual stress as a function of X-ray penetration depth. The influence of Al 2 O 3 particles on the value of the Ni coating microhardness was also analyzed.
A series of Ni/Al multilayers with different thicknesses of Ni layers was produced by a sputtering technique. The deposition parameters of optimum magnetic properties for write heads were detected by scanning the magnetic layer thickness from 0 to 70 nm. The optimum magnetic properties were decided by obtaining the saturation magnetization, Ms, coercivity, Hc and Ms/Hc ratios from the hysteresis loops. A face centered cubic (fcc) structure was established for all films. Transition surface morphology; i.e., a surface morphology between an apical + uneven structure (observed for the mono layered Al film) and an acicular + relatively smooth structure (observed for the films with Ni layer thicknesses of 30 nm and 70 nm) occurred on the surface of the film with Ni layer thickness of 10 nm. This transition surface morphology was very similar to that of the substrate as compared to the other morphologies and it may lead to relatively lower Hc value. A significant increase in Hc value was detected for Ni/Al film with Ni layer thickness of 70 nm. The increase was attributed to the irregular acicular morphology of substrate and high crystallite size of Al fcc (111). The deposition parameters of 8[Ni(10 nm)/Al(10 nm)] multilayer can be considered in order to support the higher Ms/Hc ratio which has a key role for effective technological applications of write heads.
Structure Characterization of Ni/Al 2 O 3 Composite Coatings Prepared by Electrodeposition
Solid State Phenomena, 2010
In the present study, the electrodeposition of composites consisted of metal matrix (nickel) and inert particles (hard nano-sized Al 2 O 3 oxide) has been carried out in a Watt's type bath of pH 4, at room temperature in a system with the steel rotating disk electrode. The influence of dispersed Al 2 O 3 powder on structure characteristics (morphology, phase composition, texture, residual stresses) of Ni/Al 2 O 3 coatings has been investigated. The crystallographic texture of Ni and Ni/Al 2 O 3 coatings deposited on the steel substrates was analyzed by XRD technique based on the back-reflection pole figures. The "sin 2 ψ" X-ray diffraction method was used to determine the residual stress as a function of X-ray penetration depth. The influence of Al 2 O 3 particles on the value of the Ni coating microhardness was also analyzed.
Reactive phase formation in sputter-deposited Ni/Al multilayer thin films
Journal of Materials Research, 1997
We have investigated reactive phase formation in magnetron sputter-deposited NiyAl multilayer films with a 1 : 3 molar ratio and various periodicities, L, ranging from 320 nm down to a codeposited film with zero effective periodicity. The films were studied by x-ray diffraction, differential scanning calorimetry, electrical resistance measurements, and transmission electron microscopy. We find that Ni and Al have reacted during deposition to form the B2 NiAl phase and an amorphous phase. The formation of these phases substantially reduces the driving force for subsequent reactions and explains why nucleation kinetics become important for these reactions. Depending on the periodicity, these reactions result in the formation of NiAl3 or Ni2Al9 followed by NiAl3. Detailed calorimetric analysis reveals differences in the nucleation and growth behavior of NiAl3 compared with other studies.
Journal of Alloys and Compounds, 2017
In this work, we proposed a novel mechanical alloying method to deposit Ni x-Ti x intermetallic coating on various metallic substrates using laser treatment. Three different substrates (Al-based alloy, Ti-based alloy, and hypoeutectoid steel) were used, and 50-70 µm thick Ni x Ti x coating was deposited during the process. For mechanical alloying, we used a self-constructed vibratory ball mill (single chamber) and for laser treatment, we used a "TrumpfTruDisk 1000" machine equipped with a four-dimensional control system "Servokon" designed specifically for experimental studies. Different laser beam intensities were used for laser operation. The cross-sectional microstructures of coatings were studied using a scanning electron microscope equipped with a Bruker energy-dispersive X-ray Spectrometer (EDS). Additional investigation of a cross-sectional area of one of the Ni x Ti x-coated samples was performed with field emission high-performance SEM and focused ion beam (FIB). Phase compositions of the obtained coatings, before and after laser treatment, were analyzed using X-Ray diffraction method. After the deposition process, the micro-hardness of the coatings was measured using a Vickers hardness tester. The structure and morphology of the obtained coatings were investigated.
Microstructure and properties of DC magnetron sputtered NiAl–Hf coatings
Surface & Coatings Technology, 2004
NiAl-0.1 at.% Hf coatings were successfully deposited via direct current magnetron sputtering from an alloy target onto a variety of substrates, including: glass; (1 1 1) oriented Si wafers and CMSX-4 (registered trademark of the Cannon-Muskegon ᭨ Corporation, Muskegon, MI), a second generation Ni-base superalloy. The coatings were characterized using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The as-deposited coatings were found to be crystalline, consisting of the B2 structured NiAl phase, and to exhibit dense columnar Zone T microstructures. Many of the coatings were textured and the degree of texturing was observed to change with the deposition power used and substrates that were used. NiAl coatings deposited on Si at low powers ((50 W) tended to develop random orientations, whereas coatings deposited at higher powers developed strong growth textures. Coatings deposited on Si(1 1 1) exhibited (1 1 1) textures, while coatings deposited on glass exhibited (2 1 1) textures. Thicker coatings (10-mm thick) deposited on CMSX-4 superalloy substrates at 400 W exhibited ᭨ random textures, which could be attributed to the use of higher Ar pressure during deposition. The hardness and the modulus of the different coatings, as measured via nanoindentation testing, varied with crystallographic orientation. Coatings with (1 1 1) and (2 1 1) textures exhibited higher reduced moduli and lower hardness values than randomly oriented coatings, which is in agreement with prior reports on the mechanical behavior of bulk NiAl alloys. Heat treatment of the coatings in argon gas at 500 and 1000 8C for 1 h resulted in decreases in coating hardness, but in no change in the coating modulus. The hardness change is attributed to a combination of grain growth and the annihilation of defects. ᮊ
Effect of Deposition Parameters on the Reactivity of Al/Ni Multilayer Thin Films
Coatings, 2020
Nanoscale multilayers can be used as highly localized heat sources, making them attractive for several applications, in particular for joining and as igniters. Over the last decades, academia and industry have given particular emphasis to nanoscale multilayers from the Ni–Al system. In this study, Al/Ni (V) multilayer thin films with periods of nominally 25 and 50 nm (bilayer thickness) and near equiatomic average stoichiometry were produced by d.c. magnetron sputtering from Al (99.999% pure) and Ni (93 wt % Ni, 7 wt % V) targets (vanadium was added to the Ni target to make it non-magnetic). Deposition parameters such as the substrate rotation speed and substrate bias were varied in order to evaluate their effect on the reactivity of the multilayers. The influence of in situ ion bombardment of the multilayer thin films was also studied. Phase identification was carried out by X-ray diffraction, while the microstructure was analyzed in detail by transmission electron microscopy, dist...