Thermal expansion, strength and oxidation resistance of Mo/Mo5SiB2 in-situ composites at elevated temperatures

Yoshimi, Kyosuke; Nakatani, Shinya; Nomura, Naoyuki; Hanada, Shuji

doi:10.1016/s0966-9795(03)00073-6

Cited by 77 publications

(35 citation statements)

References 19 publications

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“…1 (1), no Al added, ternary Mo/Mo 5 SiB 2 in-situ composite (composite a) exhibits a rapid mass gain at 1073 K. In the higher temperature range, i.e., 1173-1473 K, a rapid mass loss occurs at the initial oxidation stage, and then suddenly changes to the steady state oxidation in which the oxidation rate is slow and almost constant. As reported in the previous studies, this mass loss is interpreted as the volatilization of MoO 3 [10][11][12]. On the other hand, the Al addition considerably improves the oxidation resistance of the Mo/Mo 5 SiB 2 in-situ composite in the temperature range between 1073 and 1573 K. The Al addition, especially 1mol% addition, suppresses the initial mass loss more than 50%.…”

Section: Resultssupporting

confidence: 65%

“…With respect to the oxidation resistance of Mo 5 SiB 2 , Yoshimi et al [10] studied the oxidation behavior of Mo 5 SiB 2 -based alloy at elevated temperatures, and concluded that the oxidation resistance of Mo 5 SiB 2 -based alloy is not as good as that of boron-added Mo 5 Si 3 -based alloys. Furthermore, they worked on thermal expansion, strength and oxidation resistance of Mo/Mo 5 SiB 2 in-situ composites, and reported that the Mo/Mo 5 SiB 2 in-situ composite having a eutectic microstructure shows superior high temperature strength even at 1773 K [11]. However, the oxidation resistance of the Mo/Mo 5 SiB 2 in-situ composites is worse than that of Mo 5 SiB 2 [12].…”

Section: Introductionmentioning

confidence: 99%

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Oxidation Behavior of Mo-Si-B In Situ Composites

Yamauchi

Yoshimi²,

Murakami

et al. 2007

SSP

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Abstract. Isothermal oxidation behavior of Al added Mo-Si-B in-situ composites was investigated under Ar-20%O 2 and air atmosphere over the temperature range of 1073-1673 K. The Al added Mo-Si-B composites ((Mo-8.7mol%Si-17.4mol%B)-1mol%Al) were prepared by arc-melting, and homogenized at 2073 K for 24 h in an Ar-flow atmosphere. The ternary Mo-Si-B in-situ composite exhibited a rapid mass loss at the initial oxidation stage and then the passive oxidation after the substrates were sealed with borosilicate glass in the temperature range of 1173-1473 K, whereas it exhibited a rapid mass gain around 1073 K. On the other hand, the Al addition significantly improved the oxidation resistance of Mo-Si-B in-situ composites at temperatures from 1073-1573 K. These excellent oxidation resistances are considered to be due to the rapid formation of a continuous, dense scale of Al-Si-O complex oxides.

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Section: Resultssupporting

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Oxidation Behavior of Mo-Si-B In Situ Composites

Yamauchi

Yoshimi²,

Murakami

et al. 2007

SSP

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“…[1][2][3][4][5][6][7][8][9][10] These studies were usually performed in air or pure oxygen and showed that the boron and silicon in such alloys can produce a passivating borosilicate layer under high-temperature oxidation conditions. The properties of such borosilicate layers depend upon the amounts of silicon and boron in these layers.…”

Section: Introductionmentioning

confidence: 99%

The development of protective borosilicate layers on a Mo-3Si-1B (weight percent) alloy

Helmick¹,

Meier

Pettit

2005

Metall Mater Trans A

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Molybdenum-based alloys with the addition of small amounts of silicon (2 to 4.5 wt pct) and boron (ϳ1 wt pct) can form a passivating layer that protects the alloy from further rapid oxidation. When such molybdenum-based alloys are exposed to oxidizing environments at high temperatures, a borosilicate glass layer can form that will reduce the transport of oxygen to the alloy to limit further oxidation. Oxidation is then controlled by diffusion through the borosilicate glass layer. The focus of this research was to study the development of the borosilicate layer on a Mo-3Si-1B (wt pct) alloy. The oxidation of this alloy was studied in a variety of gas environments over a range of temperatures in order to elucidate the critical factors that allow it to develop a protective borosilicate glass layer. The borosilicate glass layer is protective when no continuous channels exist in the layer extending from the gas interface to the alloy interface. The borosilicate layer is believed to contain channels in the early stages of development, and the elimination of the channels is obtained by appropriate control of the temperature and gas-flow conditions, whereby MoO 3 is removed via vaporization while the borosilicate viscosity is not increased due to loss of B 2 O 3 . Once the borosilicate layer is continuous and free of channels, subsequent oxidation occurs by inward diffusion of oxygen and outward diffusion of molybdenum through this layer, with vaporization of MoO 3 occurring at the gas/borosilicate-layer interface and MoO 2 and additional borosilicate forming at the alloy/MoO 2 interface.

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“…[1][2][3][4][5][6][7] However, as these alloys have a higher density than nickel-based superalloys 2 and poor room-temperature fracture toughness, 7,8 their practical use is limited. To improve the physical properties of Mo-Si-B-based alloys, attempts have been made to include a fourth element and control the microstructure.…”

Section: Introductionmentioning

confidence: 99%

High-Temperature Compressive Properties of TiC-Added Mo-Si-B Alloys

Yoshimi

Nakamura

Yamamoto

et al. 2014

JOM

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High-temperature compressive properties of two TiC-added Mo-Si-B alloys with nominal compositions of Mo-5Si-10B-7.5TiC (70Mo alloy) and Mo-6.7Si-13.3B-7.5TiC (65Mo alloy) (at.%) were investigated. The alloys were composed of four constituent phases: Mo solid solution (Mo ss ), Mo 5 SiB 2 , (Mo,Ti)C, and (Mo,Ti) 2 C. The primary phases of the 70Mo and 65Mo alloys were Mo ss and T 2 , respectively. The compressive deformability of the 65Mo alloy was significantly limited even at 1600°C because of the elongated, coarse primary T 2 phase, whereas the 70Mo alloy had good compressive deformability and a high strength in the test-temperature range of 1000-1600°C; the peak stresses were 1800 MPa at 1000°C, 1230 MPa at 1200°C, and 350 MPa at 1600°C. At and above 1200°C, the peak stress values were more than double those of Mo-6.7Si-7.9B, Ti-Zr-Mo, and Mo-Hf-C alloys. The plastic strain in the 70Mo alloy at temperatures lower than the ductile-brittle transition temperature of T 2 was generated by plastic deformation of not only Mo ss but also of (Mo,Ti)C and (Mo,Ti) 2 C. This work indicates that (Mo,Ti)C and (Mo,Ti) 2 C play an important role in determining the high-temperature strength and deformation properties of TiC-added Mo-Si-B alloys.

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Thermal expansion, strength and oxidation resistance of Mo/Mo5SiB2 in-situ composites at elevated temperatures

Cited by 77 publications

References 19 publications

Oxidation Behavior of Mo-Si-B In Situ Composites

Oxidation Behavior of Mo-Si-B In Situ Composites

The development of protective borosilicate layers on a Mo-3Si-1B (weight percent) alloy

High-Temperature Compressive Properties of TiC-Added Mo-Si-B Alloys

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