Structure and properties of rapidly solidified dispersion-strengthened titanium alloys: Part I. Characterization of dispersoid distribution, structure, and chemistry

Sastry, Srikanth; Meschter, P. J.; O’Neal, James E.

doi:10.1007/bf02648575

Cited by 95 publications

(28 citation statements)

References 6 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: 81%

See 1 more Smart Citation

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: 81%

“…), 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%

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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“…Увеличение содержания диспрозия с 0,1 до 1 ат.% приводит к изменению морфологии микрострук-туры и фазового состава сплава (рис. [10,15,17].…”

Section: результаты и обсуждениеunclassified

“…The results of EDX measurements obtained from the areas marked in Fig. 3 [10,15,17] ка была нацелена, прежде всего, на совершенствование микроструктуры: получение более равновесной микро-структуры пластинчатого или пластинчато-глобулярно-го типа, сохранение малого размера колоний, увеличение толщины γ / α 2 пластин, а также на растворение β(В2)-фазы. Видно, что термическая обработка во всех трех сплавах приводит к формированию преимущественно пластинчатой микроструктуры (рис.…”

Section: результаты и обсуждениеunclassified

Microstructure and mechanical properties of intermetallic γ-TiAl alloy alloyed with dysprosium

Nazarova¹,

Nazarov²,

Sergeev³

et al. 2017

LoM

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In the present work, the effect of alloying with dysprosium on microstructure and compression mechanical properties of a β-solidifying γ-TiAl alloy has been studied. For this, ingots of the alloys Ti-45Al-6(Nb,Mo)-0,2B-xDy (at.%) with various additions of dysprosium (x = 0, 0,1 and 1 at.%) were melted. The as-cast alloys were homogenized and then cooled in a furnace. These conditions of the alloys were assumed as the initial cast conditions. Microstructure examination showed that Ti-45Al-6(Nb,Mo)-0,2B and Ti-45Al-6(Nb,Mo)-0,2B-0,1Dy alloys had near lamellar microstructures in the initial conditions. Alloying with 1 at.% of dysprosium caused a change in the microstructure morphology from near lamellar to mixed lamellarglobular one. The appearance of globular γ and α 2 grains in the alloy alloyed with 1 at.% of dysprosium resulted in an appreciable refinement of the γ / α 2 colonies. It was revealed that the addition of 1 at.% of dysprosium to the Ti-45Al-6(Nb,Mo)-0,2B alloy led to changing the phase composition: along with the basic γ, α 2 and β(B2)-phases an additional DyAl 2 phase was detected. Also, oxide particles Dy 2 O 3 were revealed in both alloys containing dysprosium. The alloys under study were subjected to heat treatment, which included a three-stage anneal. As a result, near lamellar structure was obtained in all alloys. It has been established that the alloys containing dysprosium in the heat treated conditions demonstrated higher values of both the strength and ductility as compared to the alloy free of dysprosium. At T = 800°C, the compression mechanical properties of the alloys were found to be similar. В работе изучали влияние легирования диспрозием на микроструктуру и механические свойства на сжатие интерме-таллидного β-затвердевающего γ-TiAl сплава. Для этого были выплавлены слитки сплавов Ti-45Al-6(Nb,Mo)-0,2B-xDy (ат.%) с различным содержанием диспрозия (x = 0, 0,1 и 1 ат.%). Слитки сплавов подвергали гомогенизационному отжигу с последующим охлаждением в печи. Данное состояние было принято за исходное литое состояние. Выпол-ненные исследования показали, что микроструктура сплавов Ti-45Al-6(Nb,Mo)-0,2B и Ti-45Al-6(Nb,Mo)-0,2B-0,1Dy в исходном состоянии преимущественно пластинчатая. Введение в сплав 1 ат.% диспрозия приводит к изменению морфологии микроструктуры от преимущественно пластинчатой к пластинчато-глобулярной. Появление глобуляр-ных γ и α 2 -зерен в сплаве с 1 ат.% диспрозия сопровождается заметным уменьшением размера γ / α 2 колоний. Было показано, что введение 1 ат.% диспрозия в сплав Ti-45Al-6(Nb,Mo)-0,2B приводит к изменению фазового состава материала: кроме основных γ, α 2 и β(В2)-фаз в сплаве была обнаружена фаза DyAl 2 . Кроме того, в микроструктуре сплавов, содержащих диспрозий, также были обнаружены оксидные частицы Dy 2 O 3 . Для всех исследованных спла-вов была выполнена термическая обработка, включавшая в себя трехстадийный отжиг. В результате во всех сплавах была получена преимущественно пластинчатая микроструктура. Установлено, что сплавы, легированные диспрози-ем, в те...

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“…[5][6][7][8][9] Rare earth elements are also considered favorable in high-temperature titanium alloys because they can adsorb the oxygen in the matrix, and the dispersed rare earth oxide particles can further strengthen the matrix alloys. [10] Creep behavior is highly important for the application of TMCs in aerospace systems. Ma et al [11] investigated the steady-state creep behavior of a TiC particle-reinforced Ti-6Al-4V composite at 823 to 923 K; the creep data covered about five orders of creep strain rates.…”

Section: Introductionmentioning

confidence: 99%

Effects of Reinforcements on Creep Resistance of Hybrid-Reinforced Titanium Matrix Composites

Xiao

Lü

Qin

et al. 2010

Metall Mater Trans A

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Hybrid-reinforced titanium matrix composites (TMCs) were in-situ synthesized by common casting and hot-working technologies. High-temperature creep behavior of the matrix titanium alloy and composites was tested at 873, 923, and 973 K in the stress range from 20 to 300 MPa. Depending on the stress levels, creep behavior of the matrix alloy and composites was divided into two stress regions. Creep resistance of the composites was significantly enhanced by the reinforcements. Threshold stresses and stress transfer effects were introduced to explain the enhancement of creep resistance. In most cases, high volume fractions of reinforcements caused a deleterious effect on the creep resistance of composites. On the other hand, types and morphologies of reinforcements were the dominant factor contributing to the enhancement of creep resistance.

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Structure and properties of rapidly solidified dispersion-strengthened titanium alloys: Part I. Characterization of dispersoid distribution, structure, and chemistry

Cited by 95 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

Microstructure and mechanical properties of intermetallic γ-TiAl alloy alloyed with dysprosium

Effects of Reinforcements on Creep Resistance of Hybrid-Reinforced Titanium Matrix Composites

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