The nature of dispersed phases in Ti-0.7at.%Er prepared by rapid solidification processing

Konitzer, D.G.; Stanley, J.T.; Loretto, M. H.; Fraser, Hamish L.

doi:10.1016/0001-6160(86)90013-1

Cited by 31 publications

(10 citation statements)

References 6 publications

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“…[1][2][3][4] The Ti-55 alloy (Ti-5Al-4Sn-2Zr-1Mo-0.25Si-1Nd) is a near-␣-high-temperature titanium alloy offering excellent tensile strength and good creep resistance up to 550 ЊC together with improved fatigue strength. [5,6] The major characteristic of the Ti-55 alloy is the addition of the rare earth element Nd (1 wt pct) to the Ti-Al-Sn-Zr-Mo-Si system.…”

Section: Introductionmentioning

confidence: 99%

Microstructure of second-phase particles in Ti-5Al-4Sn-2Zr-1Mo-0.25Si-1Nd alloy

Liu

et al. 1997

Metall Mater Trans A

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The microstructure of second-phase particles in the Ti-55 alloy was studied by scanning electron microscopy, transmission electron microscopy (TEM), and highresolution electron microscopy (HREM) observations. The second-phase particles in the conventional ingot-cast Ti-55 alloy of 1 to 15 m in diameter and uniform distribution in matrix were observed, where the majority of these particles are elliptical. The mean free path between the particles is about 46 m, and the volume fraction (pct) is 2.35. The second-phase particles typically contain Nd, Sn, and O in substantial amounts, and the content of Nd is the largest in the three elements. The elements Ti, Al, Zr, Mo and Si are depleted in the particles. The second-phase particle consists of either a dark or bright matrix and some small dark blocks dispersed within the matrix. Dark blocks match SnO (orthorhombic, a ϭ 0.500 nm, b ϭ 0.572 nm, and c ϭ 1.120 nm), and the matrix consists of a nanocrystalline phase with a stoichiometric Nd 3 Sn structure having a space group of Pm3m and lattice parameter of a ϭ 0.344 nm. The grain size of the nanocrystalline Nd 3 Sn phase is about 3 to 15 nm. The melting range of the second-phase particle is estimated to be 1042 ЊC to 1600 ЊC. The microstructure of the second-phase particles in the quenched Ti-55 alloy was also studied. Fine and uniform dispersoids (6 to 15 nm in diameter) were observed in the as-quenched state. Some lenslike particles occur at the grain boundaries, other elliptical particles appear within the grains, and some particles within the grains form rows which are parallel to the advancing liquid-solid interface. After annealing at 980 ЊC (1 to 10 hours), of the as-quenched Ti-55 alloy, coarse particles are 17 to 42 nm in average diameter, and the growth of the particles is very slow. The dispersoids in the asannealed Ti-55 alloy are identified as nanocrystalline Nd 5 Sn (orthorhombic, Pnmn, a ϭ 0.814 nm, b ϭ 1.732 nm, and c ϭ 0.814 nm) intermetallic compound, and the interface between the Nd 5 Sn 4 phase and the matrix is a typical high-angle grain boundary.

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Section: Introductionmentioning

confidence: 99%

Microstructure of second-phase particles in Ti-5Al-4Sn-2Zr-1Mo-0.25Si-1Nd alloy

Liu

et al. 1997

Metall Mater Trans A

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“…pct Er alloy microstructures were characterized by SEM and TEM after various processing conditions to compare with earlier work [2,3,11] and to show the effects of bulk liquid undercooling. pct Er alloy microstructures were characterized by SEM and TEM after various processing conditions to compare with earlier work [2,3,11] and to show the effects of bulk liquid undercooling.…”

Section: Resultsmentioning

confidence: 99%

“…[10] Processing by electron-beam melting/splat quenching [3] or laser surface melting [11] results in a single-phase ␣' Ti microstructure for erbium concentrations up to 1.8 at. [10] Processing by electron-beam melting/splat quenching [3] or laser surface melting [11] results in a single-phase ␣' Ti microstructure for erbium concentrations up to 1.8 at.…”

Section: A Rapid Solidification Of Titanium-erbium Alloysmentioning

confidence: 99%

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Interphase boundary precipitation in a Ti-1.7 at. pct Er alloy

Kral

Hofmeister

Wittig

1997

Metall Mater Trans A

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Microstructures in a Ti-1.7 at. pct Er alloy were studied in the arc-cast, rapidly solidified, and annealed conditions. Transmission electron microscopy (TEM) of the rapidly solidified materials revealed 3-to 20-nm-diameter precipitates that were distributed in regularly spaced, approximately planar sheets throughout equiaxed ␣ Ti grains. The precipitate sheet morphology is similar to the interphase boundary carbide sheets that have been documented in many alloy steels. In addition, precipitate fibers with cross sections of approximately 5 nm and up to 500 nm in length were often found adjacent to particle sheets. Electron diffraction experiments showed that the structure and lattice spacings of the sheet and fibrous particles are consistent with elemental erbium. Subsequent annealing treatments resulted in the formation of a face-centered cubic allotrope of Er 2 O 3 . The present work describes the precipitate morphologies and crystallography and discusses the applicability of current ledge growth models of interphase boundary precipitation to titanium-erbium alloys.

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“…Various methods have been proposed to prepare oxides dispersed in a titanium matrix, such as Y, Nd, and other rare earth oxides. Some of the oxides are produced by rapid solidification processes, such as laser surface melting [4][5][6][7], splat quenching [8], and rotating electrode atomizing [9][10][11]. In these studies, supersaturated solid solutions of the rare earth element in the matrix have been achieved, and then oxides precipitate during subsequent heat treatment.…”

Section: Introductionmentioning

confidence: 99%

Microstructures Evolution and Mechanical Properties of a Powder Metallurgical Titanium Alloy with Yttrium Addition

Liu

Wang

et al. 2010

Materials and Manufacturing Processes

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The mechanism of the formation of Y 2 O 3 particles and its effect on mechanical properties of Ti-Fe-Mo alloy prepared by blended elemental powder metallurgy was investigated. The results show that Y-rich particles with a low content of oxygen form in the Ti-Fe-Mo-Y alloy after sintering, instead of oxides. Only after the thermomechanical treatment can Y oxides form, so the formation of Y oxides is controlled by interfacial kinetics. More oxygen in the surrounding areas around the Y-rich particles favors the formation of oxides. The mechanical properties of powder metallurgical Ti alloy can be greatly improved by the addition of yttrium, especially after the thermomechanical treatment. The reason may be scavenging of O from the matrix and the strengthening effect of Y oxides.

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The nature of dispersed phases in Ti-0.7at.%Er prepared by rapid solidification processing

Cited by 31 publications

References 6 publications

Microstructure of second-phase particles in Ti-5Al-4Sn-2Zr-1Mo-0.25Si-1Nd alloy

Microstructure of second-phase particles in Ti-5Al-4Sn-2Zr-1Mo-0.25Si-1Nd alloy

Interphase boundary precipitation in a Ti-1.7 at. pct Er alloy

Microstructures Evolution and Mechanical Properties of a Powder Metallurgical Titanium Alloy with Yttrium Addition

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