Nanocrystalline NiCrAlY powder synthesis by mechanical cryomilling

Picas, Josep A.; Forn, Antonio; Ajdelsztajn, L.; Schoenung, Julie M.

doi:10.1016/j.powtec.2004.09.015

Cited by 32 publications

(19 citation statements)

References 7 publications

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“…The two previous cases particles ( Ref 41,42) result from metallurgical agglomeration, which is formed by cold welding. It is not anymore the case when mixtures of brittle and ductile particles where binder-induced agglomerates are primarily bonded by milling environment and can be decomposed back to their original powder form (Ref 43,44).…”

Section: Mechanical Alloying and Millingmentioning

confidence: 96%

From Powders to Thermally Sprayed Coatings

2009

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Since the early stages of thermal spray, it has been recognized that the powder composition, size distribution, shape, mass density, mechanical resistance, components distribution for composite particles play a key role in coating microstructure and thermo mechanical properties. The principal characteristics of particles are strongly linked to the manufacturing process. Coatings also depend on the process used to spray particles and spray parameters. Many papers have been devoted to the relationships existing between coating properties and structures at different scales and manufacturing processes. In many conventional spray conditions resulting in micrometric structures, among the different parameters, good powder flow ability, and dense particles are important features. Thermal plasma treatment, especially by RF plasma, of particles, prepared by different manufacturing processes, allows achieving such properties and it is now developed at an industrial scale. Advantages and drawbacks of this process will be discussed. Another point, which will be approached, is the self-propagating high-temperature synthesis, depending very strongly upon the starting composite particle manufacturing. However, as everybody knows, ''small is beautiful'' and nano-or finely structured coatings are now extensively studied with spraying of: (i) very complex alloys containing multiple elements which exhibit a glass forming capability when cooled-down, their under-cooling temperature being below the glass transition temperature; (ii) conventional micrometer-sized particles (in the 30-90 lm range) made of agglomerated nanometersized particles; (iii) sub-micrometer-or nanometer-sized particles via a suspension in which also, instead of particles, stable sol of nanometer-sized particles can be introduced; and (iv) spray solutions of final material precursor. These different processes using plasma, HVOF or sometimes flame and also cold-gas spray will be discussed together with the production of nanometer-sized particles via the chemical reaction method or by a special type of milling: the cryogenic milling process often referred to as ''cryomilling.''

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Section: Mechanical Alloying and Millingmentioning

confidence: 96%

From Powders to Thermally Sprayed Coatings

2009

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“…7 is the wt.% of Fe from 0% to 10%. This particular range was selected because usually the Fe introduced into the system during the cryomilling process will not go beyond 10 wt.%, as observed in previous research on this and other materials [26][27][28][38][39][40]. The y-axis corresponds to the mole fraction of individual phases.…”

Section: Additions Of Fe Into the Nicralmentioning

confidence: 99%

“…In recent years, cryomilling has been applied to develop nanocrystalline materials [12,[26][27][28], and the TBCs made with cryomilled NiCrAlY bond coats have demonstrated improved thermal cycle lifetime [27]. Limited evidence indicates that an unintended consequence of cryomilling is a change in the phasetransformation temperature, as indicated in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…1. In addition to the base elements of Ni, Cr, Al and Y, cryomilled NiCrAlY coatings usually contain additional elements such as Fe, N and O, which come from the stainless steel milling balls and the processing environment [26,28]. The influence of these additional components, in particular Fe, on the phase composition and phase stability of the NiCrAlY bond coat remains unclear, and is the focus of the current work.…”

Section: Introductionmentioning

confidence: 99%

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Investigation into the effects of Fe additions on the equilibrium phase compositions, phase fractions and phase stabilities in the Ni–Cr–Al system

Tang

Schoenung

2010

Acta Materialia

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“…[11] Schoenung and co-workers demonstrated that cryomilled NiCrAlY powder can be used in a spray coating process. [12] Thermal cycle tests of TBC systems with cryomilled NiCrAlY bond coats resulted in up to 3 times longer lifetime than the conventional equivalents. [13] Cryomilled NiCrAlY bond coats can have significantly improved mechanical stability at high temperatures, i.e., creep resistance, when compared to conventional materials, [14] which was attributed to the presence of ultrafine dispersoids.…”

Section: Introductionmentioning

confidence: 99%

High-Temperature Mechanical Behavior of End-of-Life Cryomilled NiCrAlY Bond Coat Materials

Funk

Eberl

et al. 2011

Metall Mater Trans A

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Previous work has demonstrated that the lifetime of atmospheric plasma sprayed thermal barrier coating (TBC) systems incorporating cryomilled NiCrAlY bond coats show superior reliability with up to 3 times longer lifetimes compared to conventional ones. These conventional and cryomilled NiCrAlY bond coats at end-of-life (after thermal cycle failure) were studied in detail in the present work with a focus on the mechanical behavior in the temperature range from room temperature to 1273 K (1000°C). The investigations were carried out using microtensile samples and the DIC technique. It turns out that the low-temperature strength of the cryomilled NiCrAlY bond coat is inferior to that of conventional ones, which might be due to a more pronounced porosity. At higher temperatures (between 1173 K and 1273 K (900°C and 1000°C)), the cryomilled bond coat shows almost twice the strength of the conventional bond coat, despite having been exposed to almost 3 times as many thermal cycles. The thermal stability of the nitride dispersoids appears to compensate for the gamma prime dissolution that typically occurs at these elevated temperatures, allowing for strength retention.

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Nanocrystalline NiCrAlY powder synthesis by mechanical cryomilling

Cited by 32 publications

References 7 publications

From Powders to Thermally Sprayed Coatings

From Powders to Thermally Sprayed Coatings

Investigation into the effects of Fe additions on the equilibrium phase compositions, phase fractions and phase stabilities in the Ni–Cr–Al system

High-Temperature Mechanical Behavior of End-of-Life Cryomilled NiCrAlY Bond Coat Materials

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