Synthesis and properties of Mo5Si3 single crystals

Chu, F.; Thoma, Dan J.; McClellan, K. J.; Peralta, Pedro; He, Ying

doi:10.1016/s0966-9795(98)00059-4

Cited by 118 publications

(66 citation statements)

References 9 publications

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“…Correspondingly, Chu et al have found that the thermal expansion is strongly anisotropic along the a and c directions in a Mo 5 Si 3 single crystal. 30) Table 2. The (Cr + Mo) content dependence of lattice parameter of Nb ss in Fig.…”

Section: Discussionmentioning

confidence: 99%

Effect of Cr Addition on Microstructure and Mechanical Properties in Nb-Si-Mo Base Multiphase Alloys

Kim¹,

Yeo

Kim

et al. 2002

Mater. Trans.

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The effects of Cr addition to Nb-22Si-5Mo alloy on phase equilibria, microstructures and mechanical properties are investigated by metallography, X-ray diffraction, scanning electron microscopy equipped with wavelength dispersive X-ray fluorescence spectroscopy and compression test at temperatures from room temperature to 1773 K. With increasing Cr content a duplex microstructure consisting of Nb 5 Si 3 and Nb ss (niobium solid solution) is changed to three-phase microstructure consisting of Nb 5 Si 3 , Nb ss and NbCr 2 . Chromium addition does not change the volume fraction of constituent phases in the two-phase alloys, whereas it increases the volume fraction of NbCr 2 , C14 Laves phase, at the expense of mostly Nb ss in the three-phase alloys. The c/a axis ratio of α-Nb 5 Si 3 phase increases with increasing (Cr + Mo) content. It is found that Cr alloying in Nb ss increases the room temperature strength due to atomic size misfit and decreases high temperature strength due to accelerated diffusion. The existence of C14 Laves phase increases high temperature strength, but degrades room temperature deformability. High temperature strength is found to be sensitive to the volume fraction and crystal structure of constituent phases as well as microstructure.

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Section: Discussionmentioning

confidence: 99%

Effect of Cr Addition on Microstructure and Mechanical Properties in Nb-Si-Mo Base Multiphase Alloys

Kim¹,

Yeo

Kim

et al. 2002

Mater. Trans.

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“…The presence of MoO 2 and Mo 9 O 26 peaks in XRD patterns from the oxide scales of the three alloys, indicates that Reaction [4] offers the most probable mechanism for the formation of MoO 3 from Mo. The anticipated oxidation reactions affecting Mo 3 Si and Mo 3 (Si m ,Al n ) phases are as follows:…”

Section: Products Of Oxidationmentioning

confidence: 95%

“…[1][2][3][4][5] Some of the recent studies [6][7][8] have shown that boron-doped Mo 5 Si 3 and Mo 5 SiB 2 possess significantly higher creep resistance than MoSi 2 . However, the major hurdles that stand in the way of their widespread application are their inherent brittleness and poor room-temperature (RT) fracture toughness.…”

Section: Introductionmentioning

confidence: 99%

Nonisothermal and Cyclic Oxidation Behavior of Mo-Si-B and Mo-Si-B-Al Alloys

Paswan

Mitra

Roy

2009

Metall Mater Trans A

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A study on nonisothermal and cyclic oxidation behavior of the reaction-hot-pressed 76Mo-14Si-10B, 77Mo-12Si- alloys has been carried out in dry air, and the results have been compared with those of isothermal tests. Nonisothermal studies by thermogravimetric (TG) analysis up to 1300°C have shown a transient mass gain between 700°C and 860°C, followed by a sharp mass loss with increased temperature, with the amount of mass change dependent on the heating rate (5°C/min to 35°C/min). The X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies of oxide scales formed on the alloys held at 790°C and 820°C for 10 or 20 minutes suggest that the oxidation of a-Mo and Mo 3 Si precedes that of Mo 5 SiB 2 . Thermal cyclic tests involving exposure at 1150°C for 1 hour, followed by either air cooling to room temperature (RT) or furnace cooling to 700°C, 800°C, or 900°C, and the subsequent examination of oxidation products, have confirmed that the formation of B 2 O 3 -SiO 2 scale provides complete and partial protection for the Mo-Si-B and Mo-Si-B-Al alloys, respectively. The results of this study show that oxidation resistance is deteriorated upon Al addition. Residual stress measured by XRD is found to be largely compressive in Mo and in mullite phases of oxide scales. Thermal shock and the mismatch in the coefficients of thermal expansion (CTEs) between the constituent phases of the oxide scale appear to be the main causes of damage.

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“…In Table 2, with Mo addition, the content of Nb does not distinctly change, while Si content decreases close to the content of Si in -Nb 5 Si 3 . And Mo content is equal to the decrement of Si content in - 14) had shown that the strength of bond rises from -Si-Si-and -Mo-Mo-chains to -Si-Mo-Si-chains. Hence, in Nb-57Si-2Mo alloys, substitution of Mo for the sites of Si Nb and formation of the strongly bonded -Si-Mo-Si-chains are responsible for the stabilization of -Nb 5 Si 3 .…”

Section: High-temperature Compression Behaviormentioning

confidence: 99%

Effect of Mo Addition on Phase Stability and High-Temperature Strength of NbSi2/Nb5Si3 Composites

Yang

Shan

et al. 2004

Mater. Trans.

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Directionally solidified NbSi 2 /Nb 5 Si 3 in-situ composites have been prepared. Scanning Electron Microscopes (SEM) and X-ray diffraction (XRD) have been used to investigate phase constitution and microstructure. It was found that microstructure and phase stability of directionally solidified alloys depended on growth rate, heat-treatment and alloying element. Compression strength was tested in the temperature range from 1473 to 1773 K and compression axes parallel to growth direction was chosen. High-temperature strength of NbSi 2 /Nb 5 Si 3 composites increased from 222.9 to 593.77 MPa at 1773 K due to Mo addition.

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Synthesis and properties of Mo5Si3 single crystals

Cited by 118 publications

References 9 publications

Effect of Cr Addition on Microstructure and Mechanical Properties in Nb-Si-Mo Base Multiphase Alloys

Effect of Cr Addition on Microstructure and Mechanical Properties in Nb-Si-Mo Base Multiphase Alloys

Nonisothermal and Cyclic Oxidation Behavior of Mo-Si-B and Mo-Si-B-Al Alloys

Effect of Mo Addition on Phase Stability and High-Temperature Strength of NbSi<sub>2</sub>/Nb<sub>5</sub>Si<sub>3</sub> Composites

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