Microstructure dependence of strength of Ir-base refractory superalloys

Yamabe-Mitari, Y.; Ro, Y.; Maruko, Tomohiro; Harada, Hiroshi

doi:10.1016/s0966-9795(98)00010-7

Cited by 59 publications

(26 citation statements)

References 17 publications

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“…The international state-of-the-art of these so-called refractory superalloys based on Ir and Rh is led by the group of Harada and Yamabe-Mitarai at the National Institute for Materials Science (NIMS) in Japan. [7][8][9][10] However, a major drawback of Ir and Rh alloys is their brittleness. [11] Fairbank and co-workers [12,13] (University of Cambridge, Cambridge, United Kingdom) focused their research on Pt-Zr and Pt-Hf binary alloys as well as on Pt-Rh-Zr and Pt-Rh-Hf ternary alloys.…”

Section: Introductionmentioning

confidence: 99%

Optimization of composition and heat treatment of age-hardened Pt-Al-Cr-Ni alloys

Hüller¹,

Wenderoth

Glatzel

et al. 2005

Metall Mater Trans A

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Section: Introductionmentioning

confidence: 99%

Optimization of composition and heat treatment of age-hardened Pt-Al-Cr-Ni alloys

Hüller¹,

Wenderoth

Glatzel

et al. 2005

Metall Mater Trans A

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“…Platinum has similar chemistry to nickel and so reacts similarly with the alloying elements and has been investigated as a potential substitute in higher temperature alloys in even more aggressive environments (Coupland et al., 1980; Fischer et al, 1997 Fischer et al, , 1999a Fischer et al, , 1999b Fischer et al, , 2001Völkl et al, 2000;Wolff and Hill, 2000). The potential of using an fcc PGM analogue was mooted several times (Bard et al, 1994), in NIMS, Japan owing to the good properties of iridium-based and rhodium-based alloys (Yamabe et al, 1996(Yamabe et al, , 1997(Yamabe et al, , 1998a(Yamabe et al, , 1998b(Yamabe et al, , 1999Yu et al, 2000), Pt-Ir alloys (YamabeMiterai et al, 2003), Pt-Al-Nb and Pt-Al-Ir-Nb alloys (Huang et al, 2004) and platinum-based alloys in South Africa (Wolff and Hill, 2000). The PGMs and nickel have similar structures (mostly fcc) and similar chemistries for the formation of similar phases.…”

Section: * Dst-nrf Centre Of Excellence In Strong Materialsmentioning

confidence: 99%

PGMs: A cornucopia of possible applications

Cornish¹

2017

J. South. Afr. Inst. Min. Metall.

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South Africa has been mining PGMs for many years and has a vested interest in the usefulness of these metals, although originally, there was little thought about downstream beneficiation and some of the products were later purchased, in effect repurchasing the raw materials. However, for about 20 years, it has been realised that in order to build wealth sustainably, at least some of the beneficiation and development has to be done in South Africa. This is because for each stage of beneficiation, the value of the commodity increases and so to buy the PGMs back in a later state is uneconomical. Also, the industries need to be established here in South Africa, so that South Africans can work in them and become part of the workforce and generate their own wealth and sustainability for their families. This is part of the rationale of the AMI.In order to drive this, as well as a viable commercial strategy, with viable and wanted products, there has to be something different in the production mixture, for example, the product has to be better, new or cheaper. This is where research is used to try and develop new capabilities, or to improve them. PGMs, application, product development. PGMs: A cornucopia of possible applications and thermal conductivity of Pt are important (Fischer, 1992). Mechanically, Pt alloyed with rhodium or iridium combine high ductility with adequate creep strength and these properties give the alloys potential for applications in the chemical, space technology and glass industries (Fischer, 2001;Whalen, 1988; Lupton, 1990). In the spacecraft industry, PGMs are used to increase the heat resistance of rocket engine nozzles. A very important application is the manufacture of high-purity optical glasses and glass fibres by using platinum-containing tank furnaces, stirrers and feeders to withstand the high temperatures, mechanical loads and corrosive attack under the glass manufacturing and shaping conditions. In glasses, outstanding purity, homogeneity and the absence of bubble inclusions can be achieved only by using platinum alloys. If ceramic melting vessels were used, ceramic particles would be loosened by erosion, which would contaminate the glass melts and so compromise the desired optical properties such as transmittance. The alloys are expensive, but there are very few other materials that could replace platinum without risk of compromising the product. Thus, this is a valuable and safe use for platinum and some of its alloys. * DST-NRF Centre of Excellence in Strong MaterialsAnother 'standard use' of PGMs is in thermocouples and this arises because of their high electrical and thermal conductivity, as well as stability due to their high corrosion resistance. Typical alloys are Pt-Rh and Pt-Ru. The thermocouples do eventually degrade in aggressive environments and become brittle, but usually without much impairment of the electrical and conductive properties.A long-standing use of PGMs is in catalysts and South Africa has established an autocatalyst manufacturing and refurbishment plant for...

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“…As with all hightemperature materials, the strength and creep resistance of Ir-based alloys at elevated temperatures would be the primary issues to resolve. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] As shownbythe binary phasediagram of Ir-Me, [15] where Me standsfor the transition metal,Irequilibrates with most of the transition metals,forming atwo-phase fccand L1 2 structure. The L1 2 -ordered phase is an intermetallic, Ir 3 Me, and fcc phase is an Ir-based solid solution.…”

Section: Introductionmentioning

confidence: 99%

“…The morphology of the L1 2 precipitate dependsonthe heat treatment and the lattice misfit between the fcc and L1 2 phase. [2,5,6] It was found that, with an increasing latticem isfit, the L1 2 phase changedf rom an irregular shape to ac ube, and, finally, to ap latelike structure. [2] Fori nstance, the L1 2 precipitate Ir 3 Hf, when therei salargel attice misfit of 2.4t o2 .7 pct, appeared as the platelike structure in the Ir-Hfbinary.Ithas been concluded that platelike L1 2 precipitates may increase the strengtho fI r-based alloys by impeding ad islocation movement.…”

Section: Introductionmentioning

confidence: 99%

Ir-Nb-Si ternary refractory superalloys with a three-phase Fcc/L12/silicide structure for high-temperature applications: Phase and microstructural evolution

Sha

Yamabe‐Mitarai

Harada

2006

Metall Mater Trans A

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To findanewp hase with the potential to improve the high-temperature strengtho fI r-based superalloys, thenovel idea of introducingsilicides into theIr-Nb binary wasimplemented.Hypoeutectic Ir-10Nb, eutectic Ir-16Nb, and hypereutectic Ir-25Nballoys were used as bases, and 5mol pct Si was added through the removal of Ir.X RD (XRD),s canning electron microscopy (SEM), and electronprobe microanalysis (EPMA) revealed the formation of athree-phase fcc/L1 2 /silicide microstructure in the Ir-Nb-Si ternarya fter Si addition. The type of silicide formed was dependent on heat-treated temperatures and Nb content. After heat treatment at 1750°Cand 1600°C, atie-triangle composed of fcc/L1 2 /silicide (Ir 2 Si) appeared in the Ir-10Nb-5Si and Ir-16Nb-5Si alloys; in the Ir-25Nb-5Si alloy, an L1 2 and silicide (Ir,Nb) 2 Si tie-line was observed. In the as-cast and 1300°Cheat-treated samples, the Ir-10Nb-5Si microstructure changedt oatwo-phase fcc/silicide structure, while the Ir-16Nb-5Si alloy maintained at hree-phase fcc/L1 2 /silicide structure.T he Ir-25Nb-5Si alloy,h owever,h ad the same phases as that at 1600°C. Silicides typically continuously or discontinuously distribute along the interdendritic regions or grain boundaries of the fcc or the L1 2 phase.W ith the additiono fS i, it was found that both the eutectic point and solid solubility of Nb in Ir would shift toward Ir.

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Microstructure dependence of strength of Ir-base refractory superalloys

Cited by 59 publications

References 17 publications

Optimization of composition and heat treatment of age-hardened Pt-Al-Cr-Ni alloys

Optimization of composition and heat treatment of age-hardened Pt-Al-Cr-Ni alloys

PGMs: A cornucopia of possible applications

Ir-Nb-Si ternary refractory superalloys with a three-phase Fcc/L12/silicide structure for high-temperature applications: Phase and microstructural evolution

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