The influence of oxygen contamination on the thermal stability and hardness of nanocrystalline Ni–W alloys

Marvel, Christopher J.; Yin, Denise; Cantwell, Patrick R.; Harmer, Martin P.

doi:10.1016/j.msea.2016.03.129

Cited by 42 publications

(14 citation statements)

References 55 publications

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“…This could be due to the limited mass sensitivity, chemical and spatial resolution of the techniques used in prior studies compared to that of APT. Regardless, it seems very probable that any non-noble nanocrystalline alloy produced by ball milling, melt spinning, electro-deposition or physical vapor deposition would be susceptible to these impurities and their effect on stabilization [39,40]. The implications of these reactions will be discussed in section 4.1. as has been used in many previous studies on nanocrystalline grain stabilization [10,42].…”

Section: Methodsmentioning

confidence: 99%

An atom probe study on Nb solute partitioning and nanocrystalline grain stabilization in mechanically alloyed Cu-Nb

et al. 2017

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Nb solute behavior and its effect on grain size stabilization in Cu-Nb alloys was studied using a combination of Vickers hardness testing, x-ray diffraction measurements, transmission electron microscopy and atom probe tomography (APT). Cu-Nb alloys with concentrations in the range from 1 to 10 at. % Nb were studied after annealing at 400°C and 800°C. The grain growth resistance at both temperatures increased with an increase in Nb solute content. For instance, after annealing at 800°C (0.74 T m), Cu-1Nb, Cu-5Nb and Cu-10Nb have a grain size that is ~8, ~14 and ~14 times respectively smaller than that of unalloyed Cu. This resistance is attributed to the formation of Nb-oxide-based clusters, elemental Nb segregation zones and large elemental (Nb)-based precipitates as observed by APT. The Nb-oxide-based clusters are the precursors of phase separation and form due to a reaction with oxygen, which is a contaminant from the milling process. Once the oxygen is consumed, the process continues and the grain boundaries accumulate more solute and begin to thicken into elemental Nb segregation zones. Eventually, Nb solute phase separates and forms Nb-based precipitates. After annealing at 400°C and 800°C, Cu-5Nb has a hardness which is approximately 2.5 times and 3 times respectively that of the hardness of unalloyed Cu after an equivalent anneal. This increase has been attributed to Hall-Petch strengthening and precipitation strengthening.

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Section: Methodsmentioning

confidence: 99%

An atom probe study on Nb solute partitioning and nanocrystalline grain stabilization in mechanically alloyed Cu-Nb

et al. 2017

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“…In Table 1, the chemical composition of the different samples measured by EDS on the sample surfaces is reported. Electrodeposited tungsten alloys normally contain some oxygen that is incorporated in form of oxides mainly in the top surface layer [13] but also within the coating, forming tungsten oxide streaks [18,41]. As it is seen from Table 1, there is no direct correlation between the Wand O content in the alloy (as well as there is no clear influence of the deposition conditions).…”

Section: Characterization Of As-plated Fe-w Coatings: Surface Morpholmentioning

confidence: 99%

“…However, it was observed that the tungsten content is not the sole factor influencing the structure and properties of the electrodeposited alloy. During the electrodeposition, various non-metallic elements can be incorporated and alter grain growth and influence the microstructure development during the thermal treatment [18,19]. Former works on W alloys with iron group metals show that after a thermal treatment the microhardness and corrosion resistance of electrodeposits increases due to formation of stable intermetallic compounds (Fe2W), which is usually observed at temperatures higher than 400 _C [6,20,21].…”

Section: Introductionmentioning

confidence: 99%

“…Carbon presence within the alloy can lead to carbide phase precipitation during annealing with important implications both for the thermal stability and the mechanical properties of the coating [19]. The presence of oxygen as impurity and its effect on both thermal stability and mechanical properties has also been investigated for Ni-W alloy [18]. However, the quantitative determination of the full composition of electrodeposits often is a challenge.…”

Section: Introductionmentioning

confidence: 99%

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In-depth characterization of as-deposited and annealed Fe-W coatings electrodeposited from glycolate-citrate plating bath

Mulone

Nicolenco

Hoffmann

et al. 2018

Electrochimica Acta

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FeW coatings with 4, 16 and 24 at.% of W were electrodeposited under galvanostatic conditions from a new environmental friendly Fe(III)-based glycolate-citrate bath. This work aims to find correlations between composition including the light elements, internal structure of the electrodeposited Fe-Walloys and functional properties of material. The obtained alloys were characterized by Glow Discharge Optical Emission Spectrometry (GD-OES), Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS), Transmission Electron Microscopy (TEM), and X-ray Diffraction (XRD). Compositional depth profiles of 10 mm thick coatings obtained by GD-OES show that the distribution of metals is uniform along the entire film thickness, while SEM imaging depicted the presence of cracks and O-and W-rich areas inside the Fe-Wcoating with 4 at.% W. In the samples with 16 and 24 at.% of W, oxygen and hydrogen are present mostly at the surface about 1 mm from the top while traces of carbon are distributed within the entire coatings. With increasing W content, the structure of the coatings changes from nanocrystalline to amorphous which was shown by XRD and TEM analysis. Also, the surface of coatings becomes smoother and brighter, that was explained based on the local adsorption of intermediates containing iron and tungsten species. Annealing experiments coupled with XRD analysis show that the thermal stability of FeW alloys increases when the W content increases, i.e. the coating with 24 at.% W retains the amorphous structure up to 600 _C, where a partially recrystallized structure was observed. Upon recrystallization of the amorphous samples the following crystalline phases are formed: a-Fe, Fe2W, Fe3W3C, Fe6W6C, and FeWO4. Hence, the FeW coatings with higher W content (>25 at.%) can be considered as suitable material for high temperature applications. Fig. 4. Compositional depth profiles as obtained by GD-OES of FeW samples of different composition: 4 at.% of W (a), 16 at.% of W (b) and 25 at.% of W(c).

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“…Besides Ni6W6C, W-rich oxide particles were consistently observed in electroplated and sputtered alloys. In electrodeposited alloys, oxide particles were measured to be of appropriate size and volume fraction to pin grain boundaries and limit grain growth [5]. In sputtered alloys, the oxide particles were observed on the columnar grain boundaries, as seen in Figure 1b.…”

mentioning

confidence: 99%

Connecting Phase Stability to the Grain Growth Behavior of Ni-W Alloys

2016

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Nanocrystalline materials are beneficial due to their promising mechanical properties. However, selecting proper alloy compositions to limit unwanted grain growth has become a challenge because of increasing difficulties in understanding nanocrystalline thermodynamics and kinetics. There is a strong dependence on accurate phase diagrams to correctly predict at which compositions certain thermal stability mechanisms are most likely active. Regardless of the stability mechanism, proper knowledge of the phase diagram is paramount to choose the best alloy composition.

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The influence of oxygen contamination on the thermal stability and hardness of nanocrystalline Ni–W alloys

Cited by 42 publications

References 55 publications

An atom probe study on Nb solute partitioning and nanocrystalline grain stabilization in mechanically alloyed Cu-Nb

An atom probe study on Nb solute partitioning and nanocrystalline grain stabilization in mechanically alloyed Cu-Nb

In-depth characterization of as-deposited and annealed Fe-W coatings electrodeposited from glycolate-citrate plating bath

Connecting Phase Stability to the Grain Growth Behavior of Ni-W Alloys

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