On the massive phase transformation regime in TiAl alloys: The alloying effect on massive/lamellar competition

Hu, D.; Huang, Aijun; Wu, Xinhua

doi:10.1016/j.intermet.2006.07.007

Cited by 108 publications

(62 citation statements)

References 21 publications

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“…Recent eorts in the development of new low--weight intermetallic TiAl-based materials for low pressure turbine blades has led to the design of a new Ti46Al8Ta [at.%] alloy [1,2].…”

Section: Introductionmentioning

confidence: 99%

Creep Deformation of Intermetallic TiAl-Based Alloy

Lapin

Staneková

2012

Acta Phys. Pol. A

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In the present work, the creep deformation behaviour of a new cast intermetallic Ti46Al8Ta [at.%] alloy is analysed. Constant load tensile creep tests were performed at initial applied stresses ranging from 200 to 400 MPa in the temperature range from 973 to 1073 K. The measured creep deformation curves are analysed and the observed deviations from calculated curves are discussed based on microstructural changes observed in the studied alloy during creep. The kinetics of creep deformation are evaluated in terms of the true activation energy for creep and the stress exponent. Creep damage initiation and propagation leading to the fracture of the creep specimens are characterized as functions of the applied stress and temperature.

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“…Recent eorts in the development of new low--weight intermetallic TiAl-based materials for low pressure turbine blades has led to the design of a new Ti46Al8Ta [at.%] alloy [1,2].…”

Section: Introductionmentioning

confidence: 99%

Creep Deformation of Intermetallic TiAl-Based Alloy

Lapin

Staneková

2012

Acta Phys. Pol. A

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“…For TiAl-based alloys, massive transformation, which is initiated by cooling from high temperature α phase in a controlled cooling rate to create massive γ phase, followed by subsequent annealing at α + γ two phase region is proven to be an effective method to refine the microstructures [5][6][7][8][9][10][11][12]. However, it is commonly agreed that a heat treatment window exists for each alloy composition; only in this window can the fully massive transformed microstructure be obtained that is suitable for the following annealing treatments, although the massive transformation is thought to be displacive only with atom rearrangement across interfaces [7,8,11,13]. For high Nb-TiAl alloys, although the microstructure is relatively finer than some other TiAl alloys during the common preparation process, further grain refinement is still necessary, since balanced mechanical properties usually exist in fine-grained fully lamellar microstructures [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Microstructure Evolution of a Ti-45Al-8.5Nb-0.2W-0.2B-0.02Y Alloy during Massive Transformation and Subsequent Annealing

Song

Wang

Xue

et al. 2018

Metals

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It has been widely reported that the microstructure refinement of TiAl alloys can be achieved by massive transformation and subsequent annealing in α 2 + γ two phase field. To achieve this goal, several heat treatment parameters must be adjusted, including the heat treatment temperature around single α phase field, the annealing temperature, and the annealing time for the precipitation of α 2 phase. Thus, a systematic study is needed for each alloy with different compositions. In this study, the heat treatment parameters for grain refinement via massive transformation of a high Nb-containing TiAl are investigated. Precipitation of α 2 phase during annealing is observed by transmission electron microscopy. It is found that 30 min at single α phase field is appropriate for the massive transformation; a full, massively transformed microstructure cannot be obtained by oil or water quenching. A short annealing time can result in a refined microstructure, whereas the sizes of the precipitated α 2 phase increases with the increase of annealing time. The α 2 phase can form at the interface of twin boundaries of the γ phase, following the Blackburn orientation relationship with both sides. The Vickers hardness is measured for the annealed samples, which remains relatively stable for different annealing times.

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“…Reducing the grain size in cast samples has been shown to improve signicantly room-temperature ductility without degradation of the creep resistance [2]. Hu et al [3] showed that Ta has low diusion coecients in both α (Ti-based solid solution) and γ phases and favours the massive transformation over the lamellar formation at low cooling rates. Based on this concept, an air--hardenable Ti46Al8Ta [at.%] alloy, requiring only air cooling from the single α phase eld to reduce the grain size of the cast components via formation of massive γ M (TiAl), was designed [3,4].…”

Section: Introductionmentioning

confidence: 99%

“…Hu et al [3] showed that Ta has low diusion coecients in both α (Ti-based solid solution) and γ phases and favours the massive transformation over the lamellar formation at low cooling rates. Based on this concept, an air--hardenable Ti46Al8Ta [at.%] alloy, requiring only air cooling from the single α phase eld to reduce the grain size of the cast components via formation of massive γ M (TiAl), was designed [3,4]. Potential industrial applications of this alloy are conditioned by optimisation of processing techniques [5,6] and a more complex understanding of mechanical properties including creep at operating temperatures.…”

Section: Introductionmentioning

confidence: 99%