Improvement of the oxidation-proof property and the scale structure of Mo3Si intermetallic alloy through the addition of chromium and aluminum elements

Ochiai, Shouichi

doi:10.1016/j.intermet.2006.01.059

Cited by 37 publications

(27 citation statements)

References 11 publications

(4 reference statements)

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“…Also, a promising solution of this problem consists in using solid solutions of mo lybdenum silicides added with chromiu m, niobiu m, titanium, tungsten and other refractory elements. The use of chromiu m as a basic additive to MoSi 2 increases the oxidation resistance of this material in the temperature range 600-900℃ [6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Features of the Solid Solution (Mo0.9,Cr0.1)Si2 Formation Depending on the State of Initial Mixture

Kud¹,

Ieremenko²,

Likhoded³

et al. 2013

MATERIALS

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The regularities of solid state synthesis of the solid solution (Mo 0.9 ,Cr 0.1 )Si 2 in vacuum have been investigated in the temperature range 400-1200℃ depending on the dispersity and energetic state of the init ial powders, name ly mo lybdenum, chro miu m and silicon. The energetic state of the in itial mixture was established to be a determin ing factor which affects the principal features of solid state interaction whereas an increase in dispersity only influences the temperature of the interaction start. When non-activated initial mixtures and ones mechanically activated in a p lanetary mill with lo w number of dru m revolutions were used, the solid solution formation proceeded owing to diffusion of silicon into meta ls through successive formation of lo wer and higher molybdenum-based silicide phases followed by their interaction. Mechanical activation in a planetary mill with high number of dru m revolutions was accompanied by not only decrease in particle size but also changes in the energetic state of the reaction mixture, which resulted in changing the regularities of the solid solution formation. Herein solid solutions on the basis of two higher molybdenum silicide phases, tetra-and hexagonal mod ifications, were formed with further poly morphic transition of the unstable high temperature hexagonal β-MoSi 2 phase into the lo w temperature tetragonal α-MoSi 2 phase. It has been established that temperature of the beginning of interaction decreases by 100℃ as compared with non-activated initial mixtures and temperature o f the end of the process depends on the amount of accu mu lated energy: under low energy mechanical activation the process is co mplete at 1200℃, while a h igh energy activation decreases this temperature by 200-400℃ depending on the duration of activation.

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Section: Introductionmentioning

confidence: 99%

Features of the Solid Solution (Mo0.9,Cr0.1)Si2 Formation Depending on the State of Initial Mixture

Kud¹,

Ieremenko²,

Likhoded³

et al. 2013

MATERIALS

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“…Classical alloying approaches regarding Mo-Si-B alloys are adding Cr and/or Al to form protective Cr-and/or Al-oxides. Formation of Al 2 O 3 through alloying with Al seems promising as well as the formation of Cr-oxide which was shown for single phase Mo 3 Si alloyed with Cr [3,4]. For Mo-Si-B alloys, the idea of adding Cr is to protect the alloy up to 900°C through the formation of a Cr-oxide scale and protection through silica takes over for higher temperatures.…”

Section: Introductionmentioning

confidence: 99%

High-Temperature Oxidation Performance of Mo-Si-B Alloys: Current Results, Developments and Opportunities

Burk

Christ

2011

AMR

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Abstract. Ni-base superalloys are approaching the melting point as their fundamental limitation. For high-temperature components one possibility aiming at a further increase of efficiency, e.g. of jet turbines, is the use of refractory metals. Mo as base material is suitable for operating temperatures far beyond 1200°C. As a consequence of the formation of volatile Mo-oxides, it exhibits no intrinsic oxidation resistance when exceeding 700°C. Mo-Si-B alloys have melting points around 2000°C and retain good mechanical properties and oxidation resistance at very high temperatures. In air, the three-phase Mo-Si-B alloy dealt with in this paper shows excellent oxidation behaviour between 900°C-1300°C as a consequence of the formation of a protective silica scale. Below 900°C, alloys of this class suffer from catastrophic oxidation, leading to an evaporation of Mo-oxide and giving rise to a linear rate law of the weight loss. A protective oxide layer is not formed as a consequence of simultaneous and competitive Mo-and Si-oxide formation. Several approaches are possible to improve the oxidation performance of Mo-Si-B alloys, especially in this moderate temperature range. These include classical alloying, e.g. with Cr aiming for protective Cr-oxide scales, addition of small amounts of reactive elements for microstructurerefinement as well as selective oxidation of silica in oxygen-deficient atmospheres prior to operation in air. The results presented show promising opportunities and indicate that an oxidation protection from room temperature up to 1300°C requires a combination of the suggested approaches.

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“…The oxidation resistance of Mo 3 Si is enhanced by the addition of Cr because of the formation of a thermally stable impervious oxide layer of Cr 2 O 3 . [9,10] The multiphase approach has led to the study of systems that provide a high level of freedom in selecting compositions of the constituent phases to obtain a more favorable balance of high-temperature strength, creep, good oxidation resistance, and at the same time, damage tolerance, particularly at lower temperatures. The ternary phase diagram of the Mo-Cr-Si alloy, including the targeted alloy composition within the black region, is shown in Figure 1…”

Section: Introductionmentioning

confidence: 99%

Studies on Synthesis and Characterization of Mo Based In Situ Composite by Silicothermy Co-reduction Process

Paul

Chakraborty

Kishor

et al. 2011

Metall Mater Trans B

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The results of an in situ synthesis of refractory metal-intermetallic composite (RMIC), Mo-16Cr-4Si (wt pct) multiphase alloy and its characterization, are presented in this study. The alloy was prepared from the oxides of molybdenum and chromium by their co-reduction with Si metal powder as a reductant. The exothermic nature of these reactions resulted in the formation of consolidated composite as a product in a single step. The thermodynamic aspects of exothermic reactions were studied by thermogravimetry/differential thermal analyzer. As-reduced alloys were remelted by arc melting and heat treated to obtain a homogenous microstructure. The evolution of phases and microstructures qA studied by X-ray diffraction, scanning electron microscopy, and energy-dispersive spectrum analysis. The multiphase alloy consisted of Mo 3 Si and discontinuous (Mo, Cr) (ss) phase with a volume percentage of 28 pct. The synthesized alloys were characterized with respect to composition, phases, microstructure, hardness, and oxidation behavior.

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Improvement of the oxidation-proof property and the scale structure of Mo3Si intermetallic alloy through the addition of chromium and aluminum elements

Cited by 37 publications

References 11 publications

Features of the Solid Solution (Mo<SUB>0</SUB><SUB>.</SUB><SUB>9</SUB>,Cr<SUB>0</SUB><SUB>.</SUB><SUB>1</SUB>)Si<SUB>2</SUB> Formation Depending on the State of Initial Mixture

Features of the Solid Solution (Mo<SUB>0</SUB><SUB>.</SUB><SUB>9</SUB>,Cr<SUB>0</SUB><SUB>.</SUB><SUB>1</SUB>)Si<SUB>2</SUB> Formation Depending on the State of Initial Mixture

High-Temperature Oxidation Performance of Mo-Si-B Alloys: Current Results, Developments and Opportunities

Studies on Synthesis and Characterization of Mo Based In Situ Composite by Silicothermy Co-reduction Process

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