Amorphous phase formation in spray deposited AlYNiCo and AlYNiCoZr alloys

Afonso, Conrado Ramos Moreira; Bolfarini, Claudemiro; Kiminami, Cláudio Shyinti; Bassim, Nabil; Kaufman, Michael J.; Amateau, M.F.; Eden, Timothy J.; Galbraith, J. M.

doi:10.1016/s1359-6462(01)00787-4

Cited by 37 publications

(40 citation statements)

References 5 publications

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“…This is why a larger fraction of featureless areas are found in the present investigation with deposition on a heated substrate acting as heat sink, compared to other studies. [11][12][13][14] It is expected that heat accumulation in the present study will be small due to rapid heat extraction, however, further solidification of deposits may lead to its temperature increase. The temperature profile in Figure 10 reveals that the temperature of the deposit reaches to a maximum of 250°C, which is well below the reported crystallization temperature of around 300°C for such alloys.…”

Section: B Microstructure Evolution In Depositmentioning

confidence: 99%

“…The major aspect of the microstructural evolution in this technique is the rapid heat extraction from the highly undercooled droplets during deposition. In the similar line of spray atomization and deposition, Afonso et al [11,12] attempted to develop Al-Y-Ni-Co alloys by spray forming at a very high gas to melt flow rate ratio of 10 m 3 /kg and found a considerable fraction of featureless areas in the spray deposit. Similarly, Guo et al [13,14] used liquid nitrogen-cooled substrate to achieve rapid heat extraction during the deposition of Al 89 La 6 Ni 5 and Al 85 Nd 5 Ni 10 alloy and observed a large fraction of glassy particle embedded in a crystalline matrix.…”

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confidence: 99%

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Formation of Nanocrystalline Matrix Composite during Spray Forming of Al83La5Y5Ni5Co2

Srivastava

Surreddi

Uhlenwinkel

et al. 2009

Metall Mater Trans A

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In the present investigation, a multicomponent glass-forming Al 83 Y 5 La 5 Ni 5 Co 2 (at. pct) alloy was spray deposited on a copper substrate to produce an 8-mm-thick plate. The substrate was 30-mm thick and heated to a temperature of 160°C prior to spray deposition. The temperature of the substrate and the deposit was measured during and after deposition. The deposits as well as oversprayed powders were characterized in terms of the microstructural features by optical microscopy and scanning electron microscopy (SEM). The phase constitution and transformation were studied by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The oversprayed powder revealed different microstructural characteristics showing crystalline, partially crystalline, and fully featureless particles. The spray deposit showed large fraction of featureless regions with embedded dendrites of 1-to 10-lm size intermetallic phases. These regions were observed to have a nanocrystalline structure with an average grain size of approximately 100 nm. The XRD analysis also revealed the nanocrystallinity in terms of a halo and peak broadening. These microstructural features have been attributed to the deposition of undercooled liquid on a highly conductive copper substrate and rapid heat extraction from the droplets due to proper metallic contact between the deposit and the substrate. These results have been discussed in light of processing conditions and the microstructural evolution of droplets in flight and during deposition.

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Section: B Microstructure Evolution In Depositmentioning

confidence: 99%

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confidence: 99%

Formation of Nanocrystalline Matrix Composite during Spray Forming of Al83La5Y5Ni5Co2

Srivastava

Surreddi

Uhlenwinkel

et al. 2009

Metall Mater Trans A

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“…Spray forming process [11][12][13][14] has been increasingly used to produce these composites in bulk dimension. [13][14][15][16] In this study, an as-spray-formed Al 89 La 6 Ni 5 nanophase composite 13) mixed together with 30% primary crystals (1 mm in diameter) was produced. In addition to the nanoscale fcc-Al crystals effect mentioned above, the primary crystals are another origin associated with the enhanced strength of the composite.…”

Section: Introductionmentioning

confidence: 99%

Thermal Stability and Mechanical Properties of Spray-Formed and Melt-Spun Al89La6Ni5 Metallic Glass Matrix Composites

et al. 2007

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A spray-formed Al 89 La 6 Ni 5 metallic glass matrix composite plate was obtained in thickness of 1 mm and diameter of 200 mm, comprising over 64% primary crystals (e.g. Al 11 La 3 ) uniformly dispersed in the glass matrix. The microstructure can not be achieved by annealing corresponding amorphous precursor. The crystals existing in the glass matrix were found to increase the hardness of the composite. Through nanoindentation test, the hardness and modulus of the composite at ambient temperature were found superior than its amorphous ribbon counterpart. The hardness of the composite was estimated with the rule of mixture from the constituents to be 4.4 GPa, which agreed well with the nanoindentation results. From loss modulus measurement and TMA test at elevated temperatures, a weak T g signal in the range of 213-240 C was revealed in the as-spray-formed composite. Furthermore, the dimension shrinkage of the composite was only 0.5% during the TMA test, which is much smaller than that of amorphous ribbon counterpart by up to 20%. The enhanced hardness by constituent second phases and the dimension stability of the composite are associated with their inherent microstructure, the primary crystals in particular.

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“…Figure 5 shows microstructures of samples extracted from the center region of the deposit obtained by optical microscopy (OM). In Figure 5a it can be observed the high volume fraction of irregular porosity (%P ≅ 8%) near the substrate surface (3 mm thick) indicating a deposition process with high volume fraction of solid particles 19,20 . Figure 5b shows the microstructure associated with the 10 mm thick region of the deposit.…”

Section: Resultsmentioning

confidence: 99%

“…The inset in the DSC graphic shows a SEM image of an amorphous (featureless) powder around 15 µm 19,20 . The presence of an amorphous phase is a reasonable hypotheses considering the cooling rates prevailing during solidification of very fine powders, 10 5 -10 6 K/s.…”

Section: Resultsmentioning

confidence: 99%

Rapid solidification of an Al-5Ni alloy processed by spray forming

et al. 2012

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Recently, intermetallic compounds have attracted much attention due to their potential technological applications as high-temperature materials. In particular the intermetallic compounds, associated with the Al-Ni binary system stand out as promising candidates for high-temperature materials for the use in harsh environments. It is expected that a bulk Al-Ni alloy may exceed the strength of many commercial materials. The great challenge in developing these alloys is to manipulate the solidification thermal parameters in order to obtain the desired microstructural features. One of the indicated routes to obtain very refined intermetallic phases dispersed in the microstructure is the spray forming process. The dendritic and eutectic growth dependences on cooling rate are already known for directionally solidified (DS) hypoeutectic Al-Ni alloys. In the case of rapidly solidified (RS) samples, extrapolations of such experimental laws are needed, which can be very helpful to estimate realistic values of high cooling rates imposed during the spray forming process. The present study aims to compare directionally solidified and spray-formed Al-5 wt. (%)Ni alloy samples with a view to providing a basis for understanding how to control solidification parameters and the as-cast microstructure. The Al-5.0 wt. (%)Ni alloy was shown to have a cellular morphology for the overspray powder size range examined (up to 500 µm). The mean cell spacing decreased from 5.0 to 1.1 µm with the decrease in the powder average diameter. It was found that the experimental cooling rates imposed during the atomization step of the overspray powder solidification varied from 10 3 to 2.10 4 K/s. The DSC trace depicted a crystallization peak of an amorphous structure fraction in the smallest Al-5.0 wt. (%)Ni alloy powder size range (<32 µm) estimating a 15 µm critical diameter of amorphous powder in the binary Al 97.5 Ni 2.5 (at%) alloy.

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Amorphous phase formation in spray deposited AlYNiCo and AlYNiCoZr alloys

Cited by 37 publications

References 5 publications

Formation of Nanocrystalline Matrix Composite during Spray Forming of Al83La5Y5Ni5Co2

Formation of Nanocrystalline Matrix Composite during Spray Forming of Al83La5Y5Ni5Co2

Thermal Stability and Mechanical Properties of Spray-Formed and Melt-Spun Al<SUB>89</SUB>La<SUB>6</SUB>Ni<SUB>5</SUB> Metallic Glass Matrix Composites

Rapid solidification of an Al-5Ni alloy processed by spray forming

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