Refining of coarse lamellar microstructure of TiAl alloys by rapid heat treatment

Wang, J.N.; Xie, Kai

doi:10.1016/s0966-9795(99)00153-3

Cited by 61 publications

(25 citation statements)

References 9 publications

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“…Ductility values were consolidated from the literature [5][6][7][8][9][10][11][28][29][30][31][32][33], and three important parameters, namly alloy chemistry, grain size, and heat treatment cycles were identified, which have major influence in ductility of the alloy. Alloy chemistry, grain size, and heat treatment cycles have important influence on ductility.…”

Section: Ductility Parameters and Data For Modelmentioning

confidence: 99%

“…To obtain desired microstructures and mechanical properties, the effect of several heat treatment cycles on aluminides has been studied at different temperatures and with varying cooling rates [9][10][11][12][13][14][15][16] and marginal improvement in ductility was reported. In this way several studies have been conducted with limited success in improving ductility of the alloy.…”

Section: Introductionmentioning

confidence: 99%

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Study on Ductility of Ti Aluminide Using Artificial Neural Network

Gupta

Mehta

Agarwala

et al. 2011

International Journal of Aerospace Engineering

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Improvement of ductility at room temperature has been a major concern on processing and application of Ti aluminides over the years. Modifications in alloy chemistry of binary alloy (Ti48 Al) and processing conditions were suggested through experimental studies with limited success. Using the reported data, the present paper aims to optimize the experimental conditions through computational modeling using artificial neural network (ANN). Ductility database were prepared, and three parameters, namely, alloy type, grain size, and heat treatment cycle were selected for modeling. Additionally, ductility data were generated from the literature for training and validation of models on the basis of linearity and considering the primary effect of these three parameters. Model was trained and tested for three different datasets drawn from the generated data. Possibility of improving ductility by more than 5% is observed for multicomponent alloy with grain size of 10-50 μm following a multistep heat treatment cycle.

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Section: Ductility Parameters and Data For Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study on Ductility of Ti Aluminide Using Artificial Neural Network

Gupta

Mehta

Agarwala

et al. 2011

International Journal of Aerospace Engineering

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“…Phase α, which appears as a result of peritectic transformation, during further cooling transforms into a lamellar crystals of ordered phases α 2 and γ, with a thickness dependent on the aluminium content and cooling rate during the transformation α→α 2 +γ [3,8]. An effective primary structure refinement of the intermetallic TiAl based alloys is the application of modifiers such as boron [9] or rare-earth metals [10], as well as special heat treatment methods [11,12]. In order to minimize the interdendritic microsegregation the homogenization annealing is conducted.…”

Section: Introductionmentioning

confidence: 99%

Fundamentals of Manufacturing Technologies for Aircraft Engine Parts Made of TiAl Based Alloys

Szkliniarz¹,

Szkliniarz²

2016

Archives of Metallurgy and Materials

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The study presents fundamentals of manufacturing technologies for aircraft engine construction elements, made of light, intermetallic TiAl based alloy, which is characterized by high relative strength and good creep and oxidation resistance. For smelting of alloy, the vacuum metallurgy methods were used, including application of induction furnace equipped with special crucibles made of isostatic-pressed, high-density graphite. To produce good quality construction element for aircraft engine, such as low-pressure turbine blade, there were methods of gravity casting from a very high temperature to the preheated shell moulds applied.

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“…[6][7][8][9][10][11][12][13][14][15][16][17] Systematically increasing the volume fraction of the lamellar constituent in a microstructure composed of equiaxed c grains and colonies of c + a 2 lamellar leads to lower creep rates and extended creep lives. [8] In addition, significantly reduced creep rates have been observed with finer lamellar spacings in FL polycrystalline microstructures containing 140 < k < 660 nm for Ti-47Al, [7] 120 < k < 450 nm for Ti-48Al, [8] 55 < k < 400 nm for Ti-45-2Nb-2Mn + 0.8 vol pct TiB 2, [15] where the characteristic lamellar spacing (k) represents the average spacing of both the a 2 and c lamellae.…”

Section: Introductionmentioning

confidence: 99%

“…However, there is a limit below which the lamellae become unstable during elevated-temperature creep. [13,14] In addition, the tensile strength [15][16][17][18] of FL TiAl microstructures has been shown to be strongly dependent on lamellar spacing, where the strength increases with the refinement of k down to 120 nm. Thus, it is believed that the elevated-temperature mechanical behavior of Ti-45-2Nb-2Mn + 0.8 vol pct TiB 2 can be improved through the refinement of k, thereby making it more attractive for LPT blade applications.…”

Section: Introductionmentioning

confidence: 99%

In Situ Observations of the Deformation Behavior and Fracture Mechanisms of Ti-45Al-2Nb-2Mn + 0.8 vol pct TiB2

Muñoz‐Moreno

Boehlert

Pérez‐Prado

et al. 2011

Metall Mater Trans A

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The deformation and fracture mechanisms of a nearly lamellar Ti-45Al-2Nb-2Mn (at. pct) + 0.8 vol pct TiB 2 intermetallic, processed into an actual low-pressure turbine blade, were examined by means of in situ tensile and tensile-creep experiments performed inside a scanning electron microscope (SEM). Low elongation-to-failure and brittle fracture were observed at room temperature, while the larger elongations-to-failure at high temperature facilitated the observation of the onset and propagation of damage. It was found that the dominant damage mechanisms at high temperature depended on the applied stress level. Interlamellar cracking was observed only above 390 MPa, which suggests that there is a threshold below which this mechanism is inhibited. Failure during creep tests at 250 MPa was controlled by intercolony cracking. The in situ observations demonstrated that the colony boundaries are damage nucleation and propagation sites during tensile creep, and they seem to be the weakest link in the microstructure for the tertiary creep stage. Therefore, it is proposed that interlamellar areas are critical zones for fracture at higher stresses, whereas lower stress, high-temperature creep conditions lead to intercolony cracking and fracture.

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Refining of coarse lamellar microstructure of TiAl alloys by rapid heat treatment

Cited by 61 publications

References 9 publications

Study on Ductility of Ti Aluminide Using Artificial Neural Network

Study on Ductility of Ti Aluminide Using Artificial Neural Network

Fundamentals of Manufacturing Technologies for Aircraft Engine Parts Made of TiAl Based Alloys

In Situ Observations of the Deformation Behavior and Fracture Mechanisms of Ti-45Al-2Nb-2Mn + 0.8 vol pct TiB2

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