Solidification of Bcc/T1/T2 three-phase microstructure in Mo–Nb–Si–B alloys

Takata, Naoki; Sekido, Nobuaki; Takeyama, Masao; Perepezko, John H.; Follett-Figueroa, M.; Zhang, C.

doi:10.1016/j.intermet.2016.01.001

Cited by 18 publications

(10 citation statements)

References 29 publications

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“…Previous studies have pointed out that adding Nb to the Mo-Si-based materials can play a satisfactory effect in improving mechanical properties due to damaging the stability of the Mo 3 Si phase [137][138][139]. However, the presence of Nb will lead to catastrophic oxidation of the material [140][141][142].…”

Section: Effects Of Rare Earth Elements On Other Mo-si Alloysmentioning

confidence: 99%

Rare Earth Elements Enhanced the Oxidation Resistance of Mo-Si-Based Alloys for High Temperature Application: A Review

Wang

et al. 2021

Coatings

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Traditional refractory materials such as nickel-based superalloys have been gradually unable to meet the performance requirements of advanced materials. The Mo-Si-based alloy, as a new type of high temperature structural material, has entered the vision of researchers due to its charming high temperature performance characteristics. However, its easy oxidation and even “pesting oxidation” at medium temperatures limit its further applications. In order to solve this problem, researchers have conducted large numbers of experiments and made breakthrough achievements. Based on these research results, the effects of rare earth elements like La, Hf, Ce and Y on the microstructure and oxidation behavior of Mo-Si-based alloys were systematically reviewed in the current work. Meanwhile, this paper also provided an analysis about the strengthening mechanism of rare earth elements on the oxidation behavior for Mo-Si-based alloys after discussing the oxidation process. It is shown that adding rare earth elements, on the one hand, can optimize the microstructure of the alloy, thus promoting the rapid formation of protective SiO2 scale. On the other hand, it can act as a diffusion barrier by producing stable rare earth oxides or additional protective films, which significantly enhances the oxidation resistance of the alloy. Furthermore, the research focus about the oxidation protection of Mo-Si-based alloys in the future was prospected to expand the application field.

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Section: Effects Of Rare Earth Elements On Other Mo-si Alloysmentioning

confidence: 99%

Rare Earth Elements Enhanced the Oxidation Resistance of Mo-Si-Based Alloys for High Temperature Application: A Review

Wang

et al. 2021

Coatings

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“…Previous studies have pointed out that adding Nb to the Mo-Si-based materials can play a satisfactory effect in improving mechanical properties due to damaging the stability of Mo3Si phase [137][138][139]. However, the presence of Nb will lead to catastrophic oxidation of the material [140][141][142].…”

Section: Effects Of Rare Earth Elements On Oxidation Behavior Of Other Mo-si Alloysmentioning

confidence: 99%

Rare Earth Elements Enhanced the Oxidation Resistance of Mo-Si-Based Alloys for High Temperature Application: A Review

Yu¹,

Fu²,

Wang³

et al. 2021

Preprint

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Traditional refractory materials such as nickel-based superalloys have been gradually unable to meet the performance requirements of advanced materials. The Mo-Si-based alloy, as a new type of high temperature structural material, has entered the vision of researchers due to its charming high temperature performance characteristics. However, its easy oxidation and even "pesting oxidation" at medium temperatures limit its further applications. In order to solve this problem, researchers have conducted large numbers of experiments and made breakthrough achievements. Based on these research results, the effects of rare earth elements like La, Hf, Ce and Y on the microstructure and oxidation behavior of Mo-Si-based alloys were systematically reviewed in the current work. Meanwhile, this paper also provided an analysis about the strengthening mechanism of rare earth elements on the oxidation behavior for Mo-Si-based alloys after discussing the oxidation process. Furthermore, the research focus about the oxidation protection of Mo-Si-based alloys in the future was prospected to expand the application field.

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“…A critical Nb content for suppressing the formation of Mo 3 Si phase was found between 24 and 26 at.%. Based on the Mo-Nb-Si-B quaternary phase diagram [12], the Nb 5 Si 3 phase should be excluded for the present compositions. The formation of this unexpected Nb 5 Si 3 should be attributed to the residue of the Nb-rich region after 30 h of milling, as supported by the above mentioned XRD and SEM analyses, and the low diffusion rates of the constituent elements during the solid-state sintering process.…”

Section: Abbreviation Of Productsmentioning

confidence: 99%

“…However, as far as the authors know, the previous works mainly focus on the stability of Mo 3 Si in a Mo-Nb-Si system theoretically [11] or experimentally [9]. Takata et al [12] studied the microstructural development of several Mo-Nb-Si-B alloys with the composition of Mo-32.6Nb-xSi-yB (at.%, hereafter all compositions Powder mixtures of elements Mo and Nb (Zhuzhou Cemented Carbide Group Co. Ltd., Zhuzhou, China), and Si and amorphous B (Sinopharm Chemical Reagent Co. Ltd., Shanghai, China), with a purity of 99% or better were weighed according to Mo-12Si-10B-xNb (abbreviated as xNb, x = 10, 20, 22, 24, 26, 28, 30, and 40). The mesh sizes of Mo, Nb, Si, and B powder particles were −300/+600 (23-48 µm), −300/+600 (23-48 µm), −200/+400 (38-75 µm) and −800/+1000 (13-18 µm), respectively.…”

Section: Introductionmentioning

confidence: 99%

Effects of Nb Content on the Mechanical Alloying Behavior and Sintered Microstructure of Mo-Nb-Si-B Alloys

Yang

Guo

2019

Metals

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Different from conventional Mo-Si-B-based alloys consisting of Moss, Mo 3 Si, and Mo 5 SiB 2 , Mo 3 Si-free Mo-Si-B-based alloys (Moss+Mo 5 Si 3 +Mo 5 SiB 2 or Moss+Mo 5 SiB 2 ) show great potentials for more excellent oxidation resistance and elevated temperature strength. In the present work, alloying element Nb was added to Mo-12Si-10B (at.%)-based alloy to suppress the formation of the Mo 3 Si phase. 20,22,24,26, 28, 30, and 40) bulk alloys were fabricated using mechanical alloying followed by cold pressing and then sintering at 1773 K for 2 h. Effects of Nb content on the mechanical alloying behavior and then sintered microstructure were studied. The addition of Nb with an amount less than 30 at.% accelerated the mechanical alloying process, but 40 at.% Nb addition decreased the process due to excessive cold welding and high powder volume. For the sintered bulk alloy prepared from the mechanically alloyed powders milled for 30 h, a critical Nb content between 24 and 26 at.% was found to suppress Mo 3 Si production and γNb 5 Si 3 phase formed in the alloys with the addition of Nb content more than 26 at.%. Prolongation of a prior milling process could facilitate the suppression of Mo 3 Si and delay the formation of niobium silicides.Metals 2019, 9, 653 2 of 15 are given in at.% unless otherwise stated) fabricated using an arc cast and directional solidification. A Moss+T1+T2 microstructure was achieved successfully. However, determined by their solidification paths, a large size T2 primary phase is inevitable in these alloys prepared via a smelting process [13,14]. The formation of this large size T2 primary phase is certainly detrimental to the fracture toughness of the alloys. Mechanical alloying (MA) followed by a sintering process facilitates the fabrication of Mo-Si-B based alloy with a continuous Moss matrix [15][16][17]. Byun et al. [18] fabricated Mo-16.9Nb-3Si-1B (wt.%) alloys using a powder metallurgical method. In their research, the Nb-containing alloy showed lower hardness (425 vs. 590 Hv) and higher fracture toughness (14.5 vs. 12.6 MPa·m 1/2 ) than those of a Nb-free alloy. It is worth noting that this Nb content is not enough to destabilize Mo 3 Si and the alloy still consists of Moss, Mo 3 Si, and Mo 5 SiB 2 . In order to suppress the Mo 3 Si phase, plenty of added Nb is necessary, which will certainly affect the MA behavior of Mo-Nb-Si-B powder mixtures. Different from the solidification process, the constituent elements in the sintering process show a lower diffusion ability. As a result, the distribution of elemental Nb in different phases in the sintered alloys may be different from that in the solidified alloys, which will affect the alloy phase constituents and the critical content of Nb addition for suppressing the Mo 3 Si phase. Besides, the prior MA degree of powder mixtures can also affect the microstructure of the sintered alloy. Therefore, the present article will focus on the effects of Nb content on the MA behavior and sintered microstructure of quaternary Mo-Nb-Si-B alloys to...

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Solidification of Bcc/T1/T2 three-phase microstructure in Mo–Nb–Si–B alloys

Cited by 18 publications

References 29 publications

Rare Earth Elements Enhanced the Oxidation Resistance of Mo-Si-Based Alloys for High Temperature Application: A Review

Rare Earth Elements Enhanced the Oxidation Resistance of Mo-Si-Based Alloys for High Temperature Application: A Review

Rare Earth Elements Enhanced the Oxidation Resistance of Mo-Si-Based Alloys for High Temperature Application: A Review

Effects of Nb Content on the Mechanical Alloying Behavior and Sintered Microstructure of Mo-Nb-Si-B Alloys

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