Effect of creep strain on microstructural stability and creep resistance of a TiAi/Ti3ai lamellar alloy

Wert, J. A.; Bartholomeusz, Michael F.

doi:10.1007/bf02647753

Cited by 19 publications

(4 citation statements)

References 19 publications

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“…Compared to the heat-treated microstructure, more equiaxed grains and breakup of the lamellar structure present at the grain boundaries, indicating that spheroidization of lamellae occur near the grain boundaries during creep deformation as reported in some published papers. 9,18,21,23) A lamellar fragmentation process associated with localized shear deformation and dynamic recrystallization were reported to be responsible for the deformation-induced spheroidization. 18,23) Spheroidization of the lamellae is a major microstructural degradation process during creep deformation, 18) leading to the formation of fine globular regions at the grain boundaries (Fig.…”

Section: Deformation Microstructuresmentioning

confidence: 99%

Grain Boundary Morphology and Its Effect on Creep of TiAl Alloys

et al. 2004

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Three kinds of microstructures with different grain boundary morphologies and their creep properties of a Ti-47Al-2Nb-2Mn+0.8 vol%TiB 2 alloy are investigated. Tensile creep tests and microstructural examinations indicate that a stabilized fine-grained fully lamellar (FGFL) microstructure with relatively smooth grain boundaries shows inferior creep resistance. A stabilized fully lamellar (FL) microstructure with well-interlocked grain boundaries and wider lamellar spacing yields reduced minimum strain rate and extended creep rupture life. Furthermore, a nearly lamellar microstructure (NL) with well-interlocked grain boundaries exhibits better creep resistance than the stabilized FGFL microstructure though it has four times wider lamellar spacing and 15 vol% equiaxed grains at the grain boundaries, but worse creep resistance than the stabilized FL microstructure. Examinations to the deformed microstructures show that grain boundary instability involving spheroidization of the lamellae is a major microstructural degradation process, resulting in fine globular regions at the grain boundaries. Voids develop along the grain boundaries, particularly in the fine globular regions, leading to intergranual fracture. It is suggested that grain boundary sliding (GBS) is operating in the stabilized FGFL microstructure, and promotes mutually with the grain boundary instability during subsequent creep deformation, resulting in increased minimum strain rate and shortened tertiary stage. The well-interlocked grain boundary inhibits the onset of GBS and enhances the grain boundary stability effectively. These results demonstrated that the grain boundary stability has a great effect on creep behavior of TiAl Alloys.

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Section: Deformation Microstructuresmentioning

confidence: 99%

Grain Boundary Morphology and Its Effect on Creep of TiAl Alloys

et al. 2004

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“…In contrast, the dynamic globularization process involves localized shear deformation at or near the grain/colony boundaries and in the kink bands. According to Wert & Bartholomeusz (1996), the lamellae seem to undergo fragmentation within these shear zones, followed by the flow of the softer phase around the fragments. Admittedly, the nucleation mechanisms for dynamic globularization are not yet fully established.…”

Section: (C) Dynamic Globularization Mechanism and Kineticsmentioning

confidence: 99%

Plastic flow, microstructure evolution, and defect formation during primary hot working of titanium and titanium aluminide alloys with lamellar colony microstructures

Semiatin

Seetharaman

Ghosh

1999

Philosophical Transactions of the Royal Society of London. Seri

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Plastic flow response, microstructure evolution, and defect formation during the primary hot working of conventional alpha/beta titanium alloys and gamma titanium aluminide alloys with two-phase lamellar colony microstructures are reviewed. The effects of initial grain/colony size, deformation rate and temperature on constitutive behaviour and the mechanisms associated with the observed flow softening are discussed. The kinetics of dynamic globularization are summarized and interpreted in terms of measured constitutive response. In addition, the mechanisms underlying failure via shear localization and cavitation during breakdown metalworking operations are described.

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“…The microstructure obtained through thermal deformation is completely spheroidized, even at a temperature lower than 500 °C. This was because deformation-induced spheroidization (DIS) [43] reduced the temperature requirement for complete spheroidization, and the crystal Previous studies have observed that the eutectic Al 4 Ca fractured after annealing at 450 • C for 3 h, began to spheroid after annealing at 500 • C for 3 h, and was completely spheroidized after annealing at 600 • C for 3 h. Figure 3c-f shows the microstructure of the as-cast Al-Ca-Fe alloy, featuring Al 4 Ca and the T phase in a lamellar morphology. With a constant volume of the eutectic phase, its spherical morphology demonstrated the lowest surface energy.…”

Section: Discussionmentioning

confidence: 99%

“…The initial distribution of the Al 4 Ca and the T phase (Figure 3c-f) was also retained after spheroidization (Figure 5), as shown in Figure 7. The microstructure obtained through thermal deformation is completely spheroidized, even at a temperature lower than 500 • C. This was because deformation-induced spheroidization (DIS) [43] reduced the temperature requirement for complete spheroidization, and the crystal defects generated during the deformation process reduced the energy required for spheroidization. Following the rolling of the Al-Ca-Fe alloy, its eutectic phase particles were observed to be finer than those in the Al-Ca alloy.…”

Section: Discussionmentioning

confidence: 99%

Convert Harm into Benefit: The Role of the Al10CaFe2 Phase in Al-Ca Wrought Aluminum Alloys Having High Compatibility with Fe

Shen,

Zhang,

Liu

et al. 2023

Materials

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The compatibility of the wrought Al-Ca alloy with the element Fe was investigated in the present study. In this work, both the Al-Ca alloy and Al-Ca-Fe alloy were synthesized through melting, casting, heat treatment, and rolling. A new ternary Al-Ca-Fe eutectic phase, identified as Al10CaFe2 with an orthorhombic structure, demonstrated enhanced performance, as revealed by nanoindentation tests. Combining the results of the nanoindentation and EBSD, it can be inferred that during the rolling and heat treatment process, the divorced eutectic phases were broken and spheroidized, and the structure of the Fe-rich alloy became finer, which promotes the formation of fine grains during the process of dynamic recrystallization and effectively hindered the grain growth during thermal treatment. Consequently, the strength of the as-rolled Al-Ca alloy was improved with the addition of 1 wt.% Fe while the ductility of the alloy was maintained. Therefore, adding Ca into the high-Fe content recycled aluminum altered the form of the Fe-containing phases in the alloy, effectively expanding the application scope of recycled aluminum alloy manufacturing. This approach also offered a method for strengthening the Al-Ca aluminum alloys. Compared to the traditional approach of reducing Fe content in alloys through metallurgical means, this study opened a new avenue for designing novel, renewable aluminum alloys highly compatible with impurity iron in scrap.

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Effect of creep strain on microstructural stability and creep resistance of a TiAi/Ti3ai lamellar alloy

Cited by 19 publications

References 19 publications

Grain Boundary Morphology and Its Effect on Creep of TiAl Alloys

Grain Boundary Morphology and Its Effect on Creep of TiAl Alloys

Plastic flow, microstructure evolution, and defect formation during primary hot working of titanium and titanium aluminide alloys with lamellar colony microstructures

Convert Harm into Benefit: The Role of the Al10CaFe2 Phase in Al-Ca Wrought Aluminum Alloys Having High Compatibility with Fe

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