Advances in phase relationship for high Nb-containing TiAl alloys

Liang, Yongfeng; Xu, Xiangjun

doi:10.1007/s12598-015-0658-3

Cited by 30 publications

(5 citation statements)

References 58 publications

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“…As shown in Figure 7, an intact Ti–43Al–3Mn–2Nb–0.1Y billet was successfully produced by one-step forging using a four-column hydraulic machine with an engineering strain of 70–80%. As known, the hot deformation of TiAl alloys is generally realized by multi-step canned forging [42,43,44]. Severe cracking tends to occur when these alloys were forged by a one-step large deformation.…”

Section: Resultsmentioning

confidence: 99%

Hot Deformation Behavior and Microstructural Evolution of a Novel β-Solidifying Ti–43Al–3Mn–2Nb–0.1Y Alloy

Cui

Xiao

et al. 2019

Materials

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In this paper, the hot deformability and mechanical properties of a novel Mn- and Nb- containing TiAl alloy were studied systematically with the use of isothermal compression experiments. The results show that the alloy has low deformation resistance and a low activation energy (392 KJ/mol), suggesting that the alloy has good hot deformability. A processing map was established, which shows that the present alloy has a smaller instability region and wider hot working window compared with other TiAl alloys. Microstructural observation shows that the initial lamellae completely transformed into fine equiaxial γ grains when the alloy was compressed at 1200 °C/0.01 s−1, which corresponds to the optimum deformation condition. Based on the above results, an intact TiAl billet was successfully fabricated by one-step large deformation using a four-column hydraulic machine. The microstructure of the billet is almost completely composed of recrystallized γ grains with large angle boundaries. Tensile testing shows the billet exhibits high tensile strength (780 MPa) and high elongation (1.44%) simultaneously, which benefits from fine γ grains with an average size of 4.9 μm. The ductile–brittle transition temperature is between 750–800 °C.

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Section: Resultsmentioning

confidence: 99%

Hot Deformation Behavior and Microstructural Evolution of a Novel β-Solidifying Ti–43Al–3Mn–2Nb–0.1Y Alloy

Cui

Xiao

et al. 2019

Materials

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“…%. Readers could refer to the phase diagram of TNB and TNM alloys in [27,77]. Second, in an actual solidification situation, the solidification process may happen under non-equilibrium conditions and different elements may distribute inhomogeneously.…”

Section: Ingot Metallurgymentioning

confidence: 99%

Microstructure Design and Its Effect on Mechanical Properties in Gamma Titanium Aluminides

Liu

Lin

Zhang

et al. 2021

Metals

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Intermetallic gamma titanium aluminides display attractive engineering properties at high temperatures of up to 750 °C. To date, they have been used in low-pressure turbine blades and turbocharger rotors in advanced aircraft and automotive engines. This review summarizes the fundamental information of the Ti–Al system. After providing the development of TiAl alloys, typical phases, microstructures and their characteristics in TiAl alloys, the paper focuses on the effects of alloying elements on the phase boundary shifting, stabilizing effects and strengthening mechanism. The relationships between chemical additions, microstructure evolution and mechanical properties of the alloy are discussed. In parallel, the processing technologies and the common heat treatment methods are described in detail, both of which are applied to optimize the mechanical properties via adjusting microstructures. On this basis, the effects from chemical composition, processing technologies and heat treatments on microstructure, which controls the mechanical properties, can be obtained. It has a certain guiding significance for tailoring the microstructures to gain desired mechanical properties.

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“…Additionally, the high-Nb TiAl alloys studied previously [15,16] had inhomogeneous microstructure and severe solute segregation (S-, band a-segregation), which may aggravate local flow during deformation, retained-bulk a 2 / c lamellae and partially recrystallized during the hot deformation process. The solute Al and Nb segregation has significant effect on stacking fault energy of TiAl alloy, which may lead to localized flow and inhomogeneous microstructure [17,18].…”

Section: Introductionmentioning

confidence: 99%

Hot Deformation Behavior and Microstructural Characteristics of Ti–46Al–8Nb Alloy

Liu

et al. 2018

Acta Metall. Sin. (Engl. Lett.)

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Hot deformation behavior, microstructural evolution and flow softening mechanism were investigated in Ti-46Al-8Nb alloy via isothermal compression approach. The true stress-strain curves exhibited typical work hardening and flow softening, in which the dependence of the peak stress on temperature and strain rate was obtained by hyperbolic sine equation with Zener-Hollomon (Z) parameter, and the activation energy was calculated to be 446.9 kJ/mol. The microstructural analysis shows that the alternate dark and light deformed ribbons of Al-rich and Nb-rich regions appeared and were associated with local flow involving solute segregation. The Al segregation promoted flow softening mainly arising from the recrystallization of c phase with low stacking fault energy. The coarse recrystallized c and several massive c phase were observed at grain boundaries. While in the case of Nb segregation, b/B2 phase harmonized bending of lamellae, combined with the growth of recrystallized c grains and a ? b ? c ? a ? c transition under conditions of temperature and stress, leading to the breakdown of a 2 /c lamellar colony. During the hot compression process, gliding and dissociation of dislocations occurred in c phase that acted as the main softening mechanism, leading to extensive c twins and cross twins in a/c lamellae and at grain boundaries. In general, homogeneous microstructure during the hot deformation process can be obtained in TiAl alloy with high Nb addition and low Al segregation. The deformation substructures intrinsically promote the formability of Ti-46Al-8Nb alloy.

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Advances in phase relationship for high Nb-containing TiAl alloys

Cited by 30 publications

References 58 publications

Hot Deformation Behavior and Microstructural Evolution of a Novel β-Solidifying Ti–43Al–3Mn–2Nb–0.1Y Alloy

Hot Deformation Behavior and Microstructural Evolution of a Novel β-Solidifying Ti–43Al–3Mn–2Nb–0.1Y Alloy

Microstructure Design and Its Effect on Mechanical Properties in Gamma Titanium Aluminides

Hot Deformation Behavior and Microstructural Characteristics of Ti–46Al–8Nb Alloy

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