Strengthened Cr-Si-base alloys for high temperature applications

Ulrich, Anke Silvia; Pfizenmaier, Petra; Solimani, Ali; Glatzel, Uwe; Galetz, Mathias C.

doi:10.1016/j.ijrmhm.2018.05.016

Cited by 13 publications

(2 citation statements)

References 49 publications

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“…Cr3Si is a very hard phase, and the hardness of Cr3Si phase on VHN basis has been reported to be more than eight times that of Cr phase [19]. Since the Cr3Si is stable at high temperatures [11,12], formation of the Cr3Si phase is expected to improve not only the wear resistance but also the strength of the Cr-Al-Si alloys at high temperatures. The microstructure of Cr-Al-Si alloys containing 10% or 20% of Al was observed and analyzed at higher magnification, as shown in Figure 2.…”

Section: Microstructure Of As-cast Cr-al-si Alloysmentioning

confidence: 99%

“…Recently, a study was conducted that focused on Cr-Al alloys containing Si for the purpose of enhancing the high-temperature hardness and strength of the Cr-Al alloys [10]. Thermal stability of Cr 3 Si phase and the possibility of improvement of high-temperature strength due to formation of it have already been reported; however, only a few research studies have been done on the formation of Cr 3 Si phase in Cr-Al-Si alloys [11,12]. In addition, although the oxidation resistance due to the formation of Cr and Al oxides in Cr-Al-Si alloys has been studied to some extent [13,14], the microstructure changes due to the addition of Si are still insufficient.…”

Section: Introductionmentioning

confidence: 99%

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Microstructure and Oxidation Resistance of Cr–Al–Si Alloys for High-Temperature Applications

Kim

2020

Coatings

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Cr–Al alloys are attracting much attention as heat- and corrosion-resistant coating materials due to their excellent high-temperature properties. In order to investigate the effect of aluminum content on the microstructure and oxidation resistance of Cr–Al–Si alloys, cast specimens were prepared by using a vacuum-arc melting furnace, and high-temperature oxidation tests were conducted with the specimens, for 1 h, at 1100 °C, in air. In the case of cast microstructure of Cr–Al–Si alloys, it consists mainly of Cr single phase, up to 5 at.% Al, and AlCr phases were additionally formed in alloys containing 10% Al or more. In the specimen with 20% Al added, CrSi phase was also found in addition to the AlCr phase. The weight change of the specimens heated for 1 h, at 1100 °C, indicated that all had excellent oxidation resistance. However, when the Al content was less than 10%, the weight gain tended to be a little lower than that of 10% or more.

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Section: Microstructure Of As-cast Cr-al-si Alloysmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Microstructure and Oxidation Resistance of Cr–Al–Si Alloys for High-Temperature Applications

Kim

2020

Coatings

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The Influence of Mo Content and Annealing on the Oxidation Behavior of Arc‐Melted Cr–xMo–8Si Alloys

Koliotassis,

White,

Galetz

2024

Adv Eng Mater

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The influence of Mo (10‐40at.%) additions to Cr‐8at.%Si was systematically studied by producing arc melted alloys and analyzing the as‐cast and annealed microstructures as well as the oxidation resistances. The majority of the alloys contained a solid solution A2 matrix with the intermetallic A15 = (Cr,Mo)3Si phase. The oxidation resistance was tested by thermogravimetric analysis (TGA) at 1200 °C in air for 50 and 100 h. Samples were characterized by XRD, SEM and EPMA (WDS). The studied Cr‐xMo‐8Si alloy series showed a beneficial effect of Mo on the corrosion behavior of the annealed arc melted alloys exposed at 1200 °C in air. An increased amount of A15 led to the formation of a continuous SiO2 scale beneath the Cr2O3 layer during high temperature exposure. The internal SiO2 layer inhibited further internal oxidation of the A15 phase. Prior annealing also influenced the oxidation behavior of the alloys. Higher annealing temperatures, resulted in an overall reduced fraction of the A15 phase, as well as coarsening, but also showed a more uniform size and distribution of the precipitates, which seems to benefit the formation of a protective duplex oxide scale. Cr‐25Mo‐8at.%Si annealed at 1350 °C for 100 h, showed the most promising oxidation behavior after exposure in air at 1200 °C for 100 h. For all of the investigated Mo contents, no nitridation was observed when compared to the Cr‐8Si reference composition. The oxide scale adhesion also was improved. For Mo >25 at.% no spallation was observed. Evaluation of the TGA data showed it follows the paralinear law, with both the growth rate, kp, and volatilization rate, kv, of Cr2O3 being reduced by adding 10‐25 at.% Mo. A binary Cr/Mo‐Si phase diagram was generated for the studied alloy series in order to determine accurate annealing conditions and estimate the stability range of the metastable σ phase.This article is protected by copyright. All rights reserved.

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Discontinuities in Oxidation Kinetics: A New Model and its Application to Cr–Si-Base Alloys

2021

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Some alloys such as many Cr-based systems show mass gain discontinuities during thermogravimetric measurements which strongly affect the oxidation kinetics. The behaviour cannot be described by the current models available in the literature. Thus, a novel $$k_\mathrm{para}$$ k para –$$k_\mathrm{lin}$$ k lin -P-model was developed to describe oxidation kinetics during the isothermal exposure of materials which show such behaviour. Beside the parabolic rate constant $$k_\mathrm{para}$$ k para and the linear mass loss constant $$k_\mathrm{lin}$$ k lin , the P-value and $$f_P$$ f P are introduced to take into account spontaneous rapid mass gains due to local oxide scale failure. The parameter P serves as a measure for the mass gain due to discontinuous events and $$f_P$$ f P is the frequency of such events. The both parameters can be related to oxide scale detachment and growth stresses. The application of the model is demonstrated for the oxidation of Cr–Si-based alloys in synthetic air at $$1200^{\circ }\hbox {C}$$ 1200 ∘ C for 100 h. For these alloys, the origin of the mass gain discontinuities is discussed and the meaning of P and $$f_P$$ f P is explained in more detail. Using this newly developed model, an insight into growth and nitridation resistance of oxide scales as well as scale adhesion is gained.

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Strengthened Cr-Si-base alloys for high temperature applications

Cited by 13 publications

References 49 publications

Microstructure and Oxidation Resistance of Cr–Al–Si Alloys for High-Temperature Applications

Microstructure and Oxidation Resistance of Cr–Al–Si Alloys for High-Temperature Applications

The Influence of Mo Content and Annealing on the Oxidation Behavior of Arc‐Melted Cr–xMo–8Si Alloys

Discontinuities in Oxidation Kinetics: A New Model and its Application to Cr–Si-Base Alloys

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