Study on the diffusion barrier effect of WSi2 layer at the MoSi2/Nb-Ti-Si based alloy interface

Yue, Gao; Guo, Xiping; Qiao, Yanqiang

doi:10.1016/j.corsci.2019.108299

Cited by 27 publications

(6 citation statements)

References 37 publications

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“…After sanding (using 200 mesh, 400 mesh, 600 mesh and 800 mesh sandpaper) and polishing, the cross-sectional microstructure and elemental distribution of the as-prepared and oxidized coatings were characterized by SEM and an electron-probe micro-analyzer (EPMA, JEOL JXA-8230, Musashino, Japan) equipped with wave dispersive X-ray spectroscopy (WDS). [41][42][43]. However, in our previous work, ZrO 2 proved to be beneficial to the high temperature oxidation resistance of silicide coating [44].…”

Section: Oxidation Test and Characterizationmentioning

confidence: 78%

“…The diffraction peaks belonging to ZrB 2 were shifted toward larger angles, which are potentially attributed to dissolution of C in the ZrB 2 lattice. No initial component such as Zr, Mo, or B 4 C was detected in the sintered samples, indicating sufficient reactions between Zr, Mo, and B 4 C. The presence of ZrO 2 in the sintered pre-layer could be attributed to the oxide impurities on the surface of the strating powders of Zr and B 4 C. Meanwhile, Zr and B 2 O 3 would react and generate ZrO 2 from 5Zr + 2B 2 O 3 = 3ZrO 2 + 2ZrB 2 [ 41 , 42 , 43 ]. However, in our previous work, ZrO 2 proved to be beneficial to the high temperature oxidation resistance of silicide coating [ 44 ].…”

Section: Resultsmentioning

confidence: 99%

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Fabrication and Oxidation Resistance of a Novel MoSi2-ZrB2-Based Coating on Mo-Based Alloy

et al. 2023

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To enhance the oxidation resistance of Mo-based TZM alloy (Mo-0.5Ti-0.1Zr-0.02C, wt%), a novel MoSi2-ZrB2 composite coating was applied on the TZM substrate by a two-step process comprising the in situ reaction of Mo, Zr, and B4C to form a ZrB2-MoB pre-layer followed by pack siliconizing. The as-packed coating was composed of a multi-layer structure, consisting of a MoB diffusion layer, an MoSi2-ZrB2 inner layer, and an outer layer of mixture of MoSi2 and Al2O3. The composite coating could provide excellent oxidation-resistant protection for the TZM alloy at 1600 °C. The oxidation kinetic curve of the composite coating followed the parabolic rule, and the weight gain of the coated sample after 20 h of oxidation at 1600 °C was only 5.24 mg/cm2. During oxidation, a dense and continuous SiO2-baed oxide scale embedded with ZrO2 and ZrSiO4 particles showing high thermal stability and low oxygen permeability could be formed on the surface of the coating by oxidation of MoSi2 and ZrB2, which could hinder the inward diffusion of oxygen at high temperatures. Concurrently, the MoB inner diffusion layer played an important role in hindering the diffusion of Si inward with regard to the TZM alloy and could retard the degradation of MoSi2, which could also improve the long life of the coating.

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Section: Oxidation Test and Characterizationmentioning

confidence: 78%

Section: Resultsmentioning

confidence: 99%

Fabrication and Oxidation Resistance of a Novel MoSi2-ZrB2-Based Coating on Mo-Based Alloy

et al. 2023

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“…The vacancies cannot be replaced due to the lack of enough atoms, thus they aggregate to form Kirkendall voids gradually. [ 70–74 ] However, these voids will grow and aggregate to generate transverse cracks. [ 75,76 ] On the one hand, devastating gaps between the coating and substrate can be caused by the transverse cracks, which destroys the bonding between layers.…”

Section: Resultsmentioning

confidence: 99%

Microstructural Characterization and Anti‐Oxidation Properties of Molybdenum Disilicide Coating on Niobium by Spent MoSi₂‐Based Materials

et al. 2020

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MoSi2 coatings are prepared using spent and commercial MoSi2 powders as raw materials to protect niobium (Nb) substrate by spark plasma sintering (SPS) technique, and the microstructure and oxidation resistance of the coatings at 1500 °C are investigated. Results showed that obvious pores are found in MoSi2 coating using commercial MoSi2 (MC coating) after SPS while MoSi2 coating using spent MoSi2 (MS coating) is dense with low porosity. (Mo,Nb)5Si3 diffusion layer is generated between MS coating and the substrate with no gap or cracks, showing excellent metallurgical bonding. After long‐term oxidation at elevated temperature, pores and exposed Mo5Si3 can be observed in the oxide scale of MC coating, while dense and complete oxide scale is obtained by MS coating. Lowest mass gain (2.78 mg cm−2) is acquired by MS coating after oxidation at 1500 °C for 40 h because SiO2 oxide scale is completely formed on the dense and bentonite‐containing coating, blocking the diffusion of oxygen at high temperature. Compared with MC coating, no further oxidation occurs inside the MS coating or substrate, exhibiting better high‐temperature oxidation resistance.

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“…Researchers have carried out the research work of MoSi 2 diffusion experiments [17][18][19][20][21][22][23][24][25][26]. Yoon et al studied the diffusion of Mo and Si in Mo/MoSi 2 diffusion couples and the growth kinetics of Mo 5 Si 3 which showed that Si is the main diffusing element [17].…”

Section: Introductionmentioning

confidence: 99%

“…Yao et al investigated the interdiffusion in the Nb/MoSi 2 diffusion couple and obtained an interdiffusion coefficient in the ternary system [22]. Yue et al showed that the introduction of WSi 2 diffusion barrier inhibited diffusion in MoSi 2 [25]. Mehrer et al studied self-diffusion in MoSi 2 using isotope tracing and measured the self-diffusion activation energy and prefactors of Mo and Si [26].…”

Section: Introductionmentioning

confidence: 99%

Self-diffusion mechanisms based defect complexes in MoSi₂

Huang¹,

Fu²,

Xu³

et al. 2021

J. Phys.: Condens. Matter

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MoSi 2 is widely concerned due to excellent electrical conductivity, oxidation resistance as a typical transition metal silicide. The high-temperature diffusion behavior is one of the important factors for the degradation of MoSi 2 coatings. However, the diffusion mechanism in MoSi 2 is still unclear. Prior theoretical work mostly focused on defect formation energy, but these are not consistent with the self-diffusion experiments because the migration behaviors were not considered. Therefore, the purpose of this work was to investigate the microscopic diffusion mechanisms of Mo and Si atoms in MoSi 2 using density functional theory and the CI-NEB method. We confirmed that the temperature-dependent vibrational contribution has a significant impact on the defect formation free energy. The isolated point defects in MoSi 2 will tend to aggregate to form defect complexes, which participate in the atomic diffusion as mediators. The defect migration behaviors of atoms for vacancy mediated, vacancy complex mediated, and antisite assisted jumps were obtained based on electronic structures analysis. The results show that Si diffusion is mediated by intrasublattice jumps of the nearest neighbor Si vacancies. Moreover, the destroyed covalent Mo-Si bonds by Si vacancies and the non-directional weak metal bonds formed by the Mo antisites and Mo atoms could improve the mobility of the Mo atom which results in the low migration barrier. The agreement between our calculations and the reported experimental results indicates that the dominant diffusion mechanism for Mo atoms is mediated by vacancy complex mediated jumps and antisite assisted jumps. It is concluded that the Si vacancy-based defect complexes are likely the diffusion mediators for Mo atom self-diffusion in MoSi 2 . This work provides a deeper insight into the connection between the atomic mechanism and the macroscopic behavior for the diffusion in the MoSi 2 , and establishes the basis for further optimizing high-temperature coating materials.

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Study on the diffusion barrier effect of WSi2 layer at the MoSi2/Nb-Ti-Si based alloy interface

Cited by 27 publications

References 37 publications

Fabrication and Oxidation Resistance of a Novel MoSi2-ZrB2-Based Coating on Mo-Based Alloy

Fabrication and Oxidation Resistance of a Novel MoSi2-ZrB2-Based Coating on Mo-Based Alloy

Microstructural Characterization and Anti‐Oxidation Properties of Molybdenum Disilicide Coating on Niobium by Spent MoSi₂‐Based Materials

Self-diffusion mechanisms based defect complexes in MoSi₂

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Study on the diffusion barrier effect of WSi2 layer at the MoSi2/Nb-Ti-Si based alloy interface

Cited by 27 publications

References 37 publications

Fabrication and Oxidation Resistance of a Novel MoSi2-ZrB2-Based Coating on Mo-Based Alloy

Fabrication and Oxidation Resistance of a Novel MoSi2-ZrB2-Based Coating on Mo-Based Alloy

Microstructural Characterization and Anti‐Oxidation Properties of Molybdenum Disilicide Coating on Niobium by Spent MoSi2‐Based Materials

Self-diffusion mechanisms based defect complexes in MoSi2

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Microstructural Characterization and Anti‐Oxidation Properties of Molybdenum Disilicide Coating on Niobium by Spent MoSi₂‐Based Materials

Self-diffusion mechanisms based defect complexes in MoSi₂