Al-Si-Ti (Aluminium - Silicon - Titanium)

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doi:10.1007/11008514_2

Cited by 3 publications

(5 citation statements)

References 33 publications

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“…579 C t 1 þ L in the Al-Si-Ti system favors the formation of t 1 . [20,28] Besides, for the hypoeutectic composition AlSi11 solid Al will persist above 579 8C as we observed in all ED-XRD maps. Later on heating, the calculated liquidus surface by Grö bner et al [28] shows that the four-phase reaction Al þ t 1 !…”

Section: Decomposition Of Ar Tih 2 Inside Liquid Alsi11 Foamssupporting

confidence: 72%

“…[21] Ti(Al x Si 1Àx ) 2 is commonly referred to as t 2 . [20] Although both silicides t 1 and Ti(Al x Si 1Àx ) 2 have different crystal structures, their most intense lines and the only visible ones in these situ experiments (due to the low counting time -7 s -and amount of compound formed) match. Thus, the diffraction map given in Figure 2c is insufficiently clear for establishing to which one of the two silicides correspond these diffraction lines.…”

Section: Foaming Alsi11 With As-received Tihmentioning

confidence: 89%

“…The first one is often referred to as t 1 , which has the general formula (Ti 1Ày Al y ) 8 (Al x Si 1Àx ) 16 where y % 0.12 and 6 x 0.25. [19,20] t 1 is tetragonal of the Zr 3 Al 4 Si 5 type and s.g. I4 1 =amd with a ¼ 3.576-3.645 Å and c ¼ 27.15 À 28.65 Å . So, t 1 becomes Ti 7 Al 5 Si 12 (a ¼ 3.570 Å and c ¼ 27.15 Å ) for y ¼ 0.12 and x ¼ 0.25.…”

Section: Foaming Alsi11 With As-received Tihmentioning

confidence: 99%

“…[19,20] The second possible ternary compound has the same crystal structure as TiSi 2 (orthorrombic, ZrSi 2 type, s.g. Cmcm with lattice parameters a ¼ 3.541 Å , b ¼ 13.617 Å , c ¼ 3.576 Å ) but as Al partially replaces Si the structure becomes pseudotetragonal. [20,21] Its general formula is Ti(Al x Si 1Àx ) 2 with 0.15 < x < 0.30 and the lattice parameters vary from a ¼ c ¼ 3.583 Å and b ¼ 13.49 Å on the TiS 2 rich side to a ¼ c ¼ 3.611 Å , whereas b remains the same on the Al rich side. [21] Ti(Al x Si 1Àx ) 2 is commonly referred to as t 2 .…”

Section: Foaming Alsi11 With As-received Tihmentioning

confidence: 99%

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Metal Foaming Studied In Situ by Energy Dispersive X‐Ray Diffraction of Synchrotron Radiation, X‐Ray Radioscopy, and Optical Expandometry

et al. 2012

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The phase transformations of TiH 2 powder inside expanding foams and their relationship with expansion behavior are still unknown, yet are of crucial importance for metal foaming. TiH 2 is still the most commonly used blowing agent for making Al-based foams by either powder metallurgical or melting routes. [1] Different pre-treatments have been empirically optimized to shift the onset of H 2 release of TiH 2 towards higher temperatures inside the melting range of the most commonly used Al-based alloys thus, obtaining larger expansion and more regular pore size foaming at ambient pressure. [2][3][4][5][6] Pressing powder mixtures under vacuum or reducing the melting temperature by alloying Al with Si, Cu, Mg, Zn, or combinations of these elements are also successful strategies for producing foams of improved pore structure and properties. [7][8][9][10][11][12][13][14] However, the more alloyed Al is, the more complex is to predict how the decomposition of TiH 2 will be inside expanding foams.The correlation between regimes of H 2 release and phase transformations of both as-received TiH 2 and pre-oxidized TiH 2Àx powders under flowing Ar were recently clarified, by using a combination of in situ diffraction methods, thermoanalysis and electron microscopy that helped to develop core shell models to describe the decomposition of the hydride in both conditions. [15] However, studies on H 2 desorption from foamable precursor material made for example by the powder metallurgical route, show different behavior than the one from loose powders, [16,4,9] which suggests that the phase transformations of TiH 2 during foaming of Al-based alloys might be different. Therefore, experiments dedicated to study in situ TiH 2 decomposition inside liquid metallic Al-based foams and its relationship with expansion are needed and motivate the present work. COMMUNICATION [*] Dr.Three synchronized methods are combined for studying in situ the foaming process of AlSi11 powder precursors containing either as-received TiH 2 or pre-oxidized TiH 2Àx . The phase transformations are followed by energy dispersive X-ray diffraction (ED-XRD) of synchrotron radiation. The internal structure of the foam is monitored by X-ray radioscopy and a video camera records the overall foam expansion. Complementary mass spectrometry follows the H 2 gas release. Phase transformations of TiH 2 and TiH 2Àx particles inside Al-Si foams are reported in this work for the first time and they are different than the ones observed for loose powders under Ar flow because the solid metal matrix initially retards H 2 outgassing, but also because after melting the liquid reacts with TiH 2 forming the ternary compounds Ti(Al x Si 1Àx ) 2 in the semi-solid state and Ti(Al 1Àx Si x ) 3 in the liquid state of the alloy. Further reasons for the larger expansion obtained when using pre-oxidized TiH 2Àx are revealed as well. The oxide shell of pre-oxidized TiH 2Àx not only shifts the onset of H 2 release towards higher temperatures, but it also hinders the reaction between blowing...

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Section: Decomposition Of Ar Tih 2 Inside Liquid Alsi11 Foamssupporting

confidence: 72%

Section: Foaming Alsi11 With As-received Tihmentioning

confidence: 89%

Section: Foaming Alsi11 With As-received Tihmentioning

confidence: 99%

Section: Foaming Alsi11 With As-received Tihmentioning

confidence: 99%

See 2 more Smart Citations

Metal Foaming Studied In Situ by Energy Dispersive X‐Ray Diffraction of Synchrotron Radiation, X‐Ray Radioscopy, and Optical Expandometry

et al. 2012

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“…The granular phase in Figure 11(b) is corresponding to the loose continuous reaction layer, and the lamellate phase is corresponding to virgate phase in the cross-sectional view of the interface. Further, as shown in Figure 12, the XRD of the phases at the corresponding surface confirmed [15], where L is the liquid phase in composition (Al: 87.835, Si: 12.1, Ti: 0.065 in at.%), (Al) is in (~98.5 at.% Al and ~1.5 at.% Si). Once the continuous compact Ti 7 Al 5 Si 12 layer was formed, the mass transfer at the triple line would be further slowed, and the wettability was improved to a very limited degree (i.e., at 600°C).…”

Section: Reactive Wetting Of Al Alloys On Metallic Substratesmentioning

confidence: 64%

Wetting of Al Alloys for Hot Dipping Coating Process

Lin¹,

Sui²,

Yu³

2019

Wettability and Interfacial Phenomena - Implications for Material Processing

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Wetting phenomenon, as a basic physical process, also relates to the many material processes, such as coating process, brazing or soldering process, casting, preparation of MMCs, etc. In this chapter, the method of wetting characterization at the high temperatures was presented (especially for the metallurgical melts), also the wetting behavior and mechanism of Al alloys (4043 and 6061 alloys) on the different metallic substrates at isothermal dwelling process as well as the characteristics and formation mechanism of precursor film were discussed. Thermodynamics of segregation of solute element were also discussed, which can be predicted by the thermodynamic model. We believe the content of this chapter would be a guidance for hot dipping process based on the wetting theories.

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Reactive wetting of Ti-6Al-4V alloy by molten Al 4043 and 6061 alloys at 600–700°C

Lin

Jin

et al. 2017

International Journal of Materials Research

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Wetting of Ti-6Al-4V alloy by two industrial grade Al alloys (i. e., Al 6061 and 4043 alloys) was studied using the sessile drop method at 600–700 °C under high vacuum. Al/Ti-6Al-4V is a typical reactive wetting system with good final wettability accompanied by the formation of precursor film which is actually an extended reaction layer. The formation mechanism for the precursor film is “subcutaneous infiltration”. The small amount of alloying element Si in the alloys can cause significant segregation at the liquid/solid interface which satisfies the thermodynamic condition. The wetting behavior can be described by the classic reaction product control models, and Ti7Al5Si12 decomposition and Al3Ti formation correspond to the two spreading stages. The small difference in alloying elements in Al 6061 and 4043 resulted in distinctly different interface structures, formation of precursor film and spreading dynamics, especially for the Si segregation at the interface.

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Al-Si-Ti (Aluminium - Silicon - Titanium)

Cited by 3 publications

References 33 publications

Metal Foaming Studied In Situ by Energy Dispersive X‐Ray Diffraction of Synchrotron Radiation, X‐Ray Radioscopy, and Optical Expandometry

Metal Foaming Studied In Situ by Energy Dispersive X‐Ray Diffraction of Synchrotron Radiation, X‐Ray Radioscopy, and Optical Expandometry

Wetting of Al Alloys for Hot Dipping Coating Process

Reactive wetting of Ti-6Al-4V alloy by molten Al 4043 and 6061 alloys at 600–700°C

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