Rapid solidification processing of titanium alloys

Suryanarayana, C.; Froes, F. H.; Rowe, R.G.

doi:10.1179/imr.1991.36.1.85

Cited by 61 publications

(19 citation statements)

References 86 publications

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“…[9] Similarly, the addition of Y, Er, Nd, Dy, Gd, and La to commercial-purity Ti produces a uniform distribution of fine incoherent dispersoids that significantly refine the microstructure by inhibiting grain boundary migration during recrystallization and restricting grain growth at elevated temperature. [7][8][9][10][11] Early investigations gave out various crystal structures of the rare earth-contained dispersoids in the titanium alloys such as Er 2 O 3 , Al 3 La, La, La 2 Sn, Y 5 Sn 3 , and Ti-Re-O-C et al [4,8,[12][13][14][15] In our present investigations, however, the observations are very different from the preceding results.…”

Section: Introductioncontrasting

confidence: 82%

“…Melt-extracted Ti-6Al-2Sn-4Zr-1Er, consolidated by hot isostatic pressing and extrusion and subsequently annealed for 1 hour at 950 ЊC, had a dispersoid 20 to 40 nm in diameter. [15] Therefore, RE-containing Ti alloys serviced for high-temperature application are promising. This article describes the size, shape, and distribution of the second-phase particles in the conventional ingot-cast and quenched Ti-55 alloys after heat treatment, and the structures of the particles are determined using high-resolution electron microscopy (HREM) and transmission electron microscopy (TEM).…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, these elements form stable dispersoids in the titanium matrix, providing dispersion strengthening in the elevated temperature. [12,14,15] It has been reported that the generation of a fine dispersion of hard, insoluble CeO 2 particles in a ␣-Ti matrix results in an alloy with superior stress-rupture properties and improved creep ductility. [9] Similarly, the addition of Y, Er, Nd, Dy, Gd, and La to commercial-purity Ti produces a uniform distribution of fine incoherent dispersoids that significantly refine the microstructure by inhibiting grain boundary migration during recrystallization and restricting grain growth at elevated temperature.…”

Section: Introductionmentioning

confidence: 99%

“…), and an actinide element (Th). [7][8][9][10][11][12][13][14][15] By and large, all these elements have negligible solubility in titanium at room temperature. Furthermore, these elements form stable dispersoids in the titanium matrix, providing dispersion strengthening in the elevated temperature.…”

Section: Introductionmentioning

confidence: 99%

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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: Introductioncontrasting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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 addition of erbium and other rare-earth elements produces dispersoids that consequently resist coarsening at least up to 800°C. 6 However, further optimization is required, particularly efforts to increase the volume fraction of secondphase particles.…”

Section: Titaniummentioning

confidence: 99%