Effect of small aluminum additions on microstructure and mechanical properties of molybdenum di-silicide

Mitra, Rahul; Rao, V. V. Rama; Rao, A. Venugopal

doi:10.1016/s0966-9795(98)00064-8

Cited by 48 publications

(47 citation statements)

References 40 publications

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“…Mechanical behavior of polycrystalline MoSi 2 has been reported similar to that of brittle ceramics [24]. In present study, MoSi 2 -5 vol%Al 2 O 3 composites prepared at 1400 1C exhibited excellent mechanical properties (Table 1): Vicker's hardness Hv 11.14 GPa, bending strength σ b 435 MPa and fracture toughness K IC 4.53 MPa m 1/2 .…”

Section: Resultssupporting

confidence: 70%

Synthesis, microstructure and properties of MoSi 2 –5 vol%Al 2 O 3 composites

Wang

Feng

Niu

et al. 2014

Ceramics International

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Section: Resultssupporting

confidence: 70%

Synthesis, microstructure and properties of MoSi 2 –5 vol%Al 2 O 3 composites

Wang

Feng

Niu

et al. 2014

Ceramics International

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“…[7] Dislocation generation is, however, expected at the MoSi 2 -SiC interfaces in the composites, because of a mismatch in the coefficient of thermal expansion. Low-angle boundary formation under static recovery conditions [55] needs a sufficiently high density of dislocations for the generation of high interdislocation interaction stresses, which act as a driving force for dislocation rearrangement.…”

Section: Studies Of Deformed Samplesmentioning

confidence: 99%

High-temperature deformation behavior of coarse- and fine-grained MoSi2 with different silica contents

Mitra

Prasad

Kumari

et al. 2003

Metall Mater Trans A

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The elevated-temperature deformation behavior of polycrystalline molybdenum disilicide (MoSi 2 ), in the range of 1000 °C to 1350 °C at the strain rates of 10 Ϫ3 , 5 ϫ 10 Ϫ4 , or 10 Ϫ4 s Ϫ1 , has been studied. The yield strength, post-yield flow behavior comprising strain hardening and serrations, as well as some of the deformation microstructures of reaction-hot-pressed (RHP) MoSi 2 samples, processed by hot pressing an elemental Mo ϩ Si powder mixture and having a grain size of 5 mm and oxygen content of 0.06 wt pct, have been compared with those of samples prepared by hot pressing of commercial-grade Starck MoSi 2 powder, with a grain size of 27 mm and oxygen content of 0.89 wt pct. While the fine-grained RHP MoSi 2 samples have shown higher yield strength at relatively lower temperatures and higher strain rates, the coarse-grained Starck MoSi 2 has a higher yield at decreasing strain rates and higher temperatures. The work-hardening or softening characteristics are dependent on grain size, temperature, and strain rate. Enhanced dislocation activity and dynamic recovery, accomplished by arrangement of dislocations in low-angle boundaries, characterize the deformation behavior of fine-grained RHP MoSi 2 at a temperature of 1200 °C and above and are responsible for increased uniform plastic strain with increasing temperature. The silica content appears to be less effective in degrading the high-temperature yield strength if the grain size is coarse, but leads to plastic-flow localization and strain softening in Starck MoSi 2 . Serrated plastic flow has also been observed in a large number of samples, mostly when deformed at specific combinations of strain rates and temperatures.

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“…The appearance of silica is due to the oxidation process during milling and formation of Mo 5 Si 3 phase is a consequence of the deficiency of silicon as proposed by e.g. Mitra et al 13) Milling in Ar gas suppressed the oxidation process and thus results in less silica and Mo 5 Si 3 phase. Further observations of the other alloys reveal that the alloys made from powders milled in air contain more oxide particles compared to their counterparts milled in Ar gas.…”

Section: Mechanical Propertiesmentioning

confidence: 91%

“…Attempts have been made on MoSi 2 with a variety of alloy elements such as W, V, Re, Cr, Nb, Al, and B. [9][10][11][12][13] Aluminum addition was found to be extremely effective in eliminating the grain boundary amorphous silica phases, which are generally considered to be the vital detriment to the hightemperature creep resistance of MoSi 2 alloys. 14) Nb is also an interesting alloy element for MoSi 2 .…”

Section: Introductionmentioning

confidence: 99%

Preparation of MoSi<SUB>2</SUB>-X(X=B, Al, Nb) Alloys by Mechanical Alloying and Pulse Discharge Sintering Process

2002

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Mechanical alloying and pulse discharge sintering (MA-PDS) process was employed to fabricate MoSi 2 alloys with additions of Al, B or Nb alloy elements. Microstructure and mechanical properties of these alloys were investigated. An exothermic behavior was identified during milling. This process is related to the reaction of each element to synthesize intermetallic MoSi 2 . The MoSi 2 alloys fabricated by MA-PDS process showed a very fine microstructure compared to that sintered from the commercial MoSi 2 alloy powders. Significant hardness increase was found due to the refinement of the binary MoSi 2 microstructure. Alloys made from powders milled in air show higher hardness compared to those in Ar gas. This was because of the oxides formed during milling process.

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Effect of small aluminum additions on microstructure and mechanical properties of molybdenum di-silicide

Cited by 48 publications

References 40 publications

Synthesis, microstructure and properties of MoSi 2 –5 vol%Al 2 O 3 composites

Synthesis, microstructure and properties of MoSi 2 –5 vol%Al 2 O 3 composites

High-temperature deformation behavior of coarse- and fine-grained MoSi2 with different silica contents

Preparation of MoSi<SUB>2</SUB>-X(X=B, Al, Nb) Alloys by Mechanical Alloying and Pulse Discharge Sintering Process

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