The critical pressure and impeding pressure of Al evaporation during induction skull melting processing of TiAl

Guo, Jingjie; Jia, Jinyuan; Fu, Hengzhi; Liu, Guizhong; Su, Yanqing; Ding, Hongsheng

doi:10.1007/s11661-002-0311-2

Cited by 14 publications

(5 citation statements)

References 6 publications

(4 reference statements)

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“…A considerable reduction of shrinkage cavities could only be achieved by means of a close control of process temperatures. Although melting under vacuum allows to get rid of gas porosities, as already stressed in some papers [16][17][18], it causes aluminium loss that requires during the charge material preparation a careful calculation of aluminium excess. Usually, the melting conditions of TiAl lie in the free evaporation area, thus the evaporation loss must be taken into account for the composition control.…”

Section: Resultsmentioning

confidence: 99%

“…Usually, the melting conditions of TiAl lie in the free evaporation area, thus the evaporation loss must be taken into account for the composition control. Experiments reported in literature [18] highlight that there exists a critical pressure and an impeding pressure for the evaporation losses of Al in a TiAl melt during the melting process under vacuum. When the vacuum pressure is less than the critical pressure, the evaporation of components takes on a state of free evaporation.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Effects of the manufacturing process on fracture behaviour of cast TiAl intermetallic alloys

Brotzu

Felli

Pilone

2013

Frattura Ed Integrità Strutturale

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The γ -TiAl based intermetallic alloys are interesting candidate materials for high-temperature applications with the efforts being directed toward the replacement of Ni-based superalloys. TiAl-based alloys are characterised by a density (3.5-4 g/cm 3 ) which is less than half of that of Ni-based superalloys, and therefore these alloys have attracted broad attention as potential candidate for high-temperature structural applications. Specific composition/microstructure combinations should be attained with the aim of obtaining good mechanical properties while maintaining satisfactory oxidation resistance, creep resistance and high temperature strength for targeted applications. Different casting methods have been used for producing TiAl based alloys. In our experimental work, specimens were produced by means of centrifugal casting. Tests carried out on several samples characterised by different alloy compositions highlighted that solidification shrinkage and solid metal contraction during cooling produce the development of relevant residual stresses that are sufficient to fracture the castings during cooling or to produce a delayed fracture. In this work, crack initiation and growth have been analysed in order to identify the factors causing the very high residual stresses that often produce explosive crack propagation throughout the casting.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Effects of the manufacturing process on fracture behaviour of cast TiAl intermetallic alloys

Brotzu

Felli

Pilone

2013

Frattura Ed Integrità Strutturale

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“…[21][22][23] The ingot was subjected to a hot isostatic pressing (HIP) at 1250 C and 150 MPa for 4 h to remove cast porosity. For producing a fine-grained microstructure, the HIPed material was then subjected to a multi-step thermomechanical process involving multiple steps of forging.…”

Section: Methodsmentioning

confidence: 99%

Superplasticity and Superplastic Diffusion Bonding of a Fine-Grained TiAl Alloy

Zhu

Zhao

et al. 2005

Mater. Trans.

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Superplasticity and superplastic diffusion bonding in a TiAl alloy with a fine-grained duplex microstructure have been investigated in order to fabricate TiAl alloy products using a combination process of superplastic forming with diffusion bonding. Superplastic tensile tests were carried out at temperatures ranging from 1000 to 1100 C, and at strain rates ranging from 10 À5 to 10 À3 s À1 . A low superplastic flow stress of less than 25 MPa was observed at 1100 C and at a strain rate of 8:3 Â 10 À5 s À1 . Under this condition, a tensile elongation of 300% and a strain rate sensitivity coefficient of over 0.5 were obtained. Furthermore, superplastic diffusion bonding under a low pressure of 10 MPa was conducted. Defect-free bonds were achieved at 1100 C for holding 1 h. It is suggested that the low superplastic flow stress at 1100 C allows a significant plastic flow between the two contacted surfaces, resulting in a full contact of the surfaces, which is necessary for the sound bonds. Finally, a twosheet part of spherical dome was successfully produced from this alloy.

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“…Among titanium-based materials, the most commonly used types are Ti-Al-X alloys. However, their production technologies are associated with many difficulties due to three factors: a high smelting temperature, high reactivity of titanium with the crucible materials and a potential for evaporation of the alloy components with higher vapour pressures than that of the metal matrix during the smelting process [1][2][3][4][5][6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Archives of Foundry Engineering

Smalcerz,

Blacha,

Łabaj

2020

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Titanium alloys belonging to the group of modern metallic materials used in many industries, including the aerospace industries. Induction crucible vacuum furnaces and induction furnaces with cold crucible are most commonly used for their smelting. When operating these devices, one can deal with an adverse phenomenon of decrease in the content of alloy elements that are characterized by higher equilibrium vapour pressure than the matrix metal or titanium, in the metal bath. In the paper, results of the study on aluminium evaporation from the Ti-Al-Nb, Ti-Al-V and Ti-Al alloys (max 6.2 % wt.) during smelting in a vacuum induction melting (VIM) furnace are presented. The experiments were performed at 10 to 1000 Pa for 1973 K and 2023 K. A significant degree of aluminium loss has been demonstrated during the analysed process. The values of relative aluminium loss for all the alloys ranged from 4 % to 25 %. Lowering the pressure in the melting system from 1000 Pa to 10 Pa resulted in increased values of aluminium evaporation flux from 4.82⋅10 -5 to 0.000327 g⋅cm -2 ⋅s -1 for 1973 K and from 9.28⋅10 -5 to 0.000344 g⋅cm -2 ⋅s -1 for 2023 K. The analysis of the results obtained took into account the value of the actual surface of the liquid metal. In the case of melting metals in an induction furnace, this surface depends on the value of power emitted in the charge. At greater power, we observe a significant increase in the bath surface due to the formation of a meniscus.

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The critical pressure and impeding pressure of Al evaporation during induction skull melting processing of TiAl

Cited by 14 publications

References 6 publications

Effects of the manufacturing process on fracture behaviour of cast TiAl intermetallic alloys

Effects of the manufacturing process on fracture behaviour of cast TiAl intermetallic alloys

Superplasticity and Superplastic Diffusion Bonding of a Fine-Grained TiAl Alloy

Archives of Foundry Engineering

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