Effects of Annealing and Pressure on Devitrification and Mechanical Properties of Amorphous Al87Ni7Gd6

Wesseling, P.; Ko, Byung-Hyun; Vatamanu, Luciano O.; Shiflet, G. J.; Lewandowski, John J.

doi:10.1007/s11661-007-9384-2

Cited by 18 publications

(8 citation statements)

References 24 publications

(47 reference statements)

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“…Similar changes to hardness have been reported after exposure to high temperatures for other metallic glass systems. [7,16] B. Thermal Exposure Effects on Microhardness Figure 3 shows the effect of exposure time on microhardness (plotted in GPa) evolution obtained on six separate samples held at 150°C, 275°C, 300°C, 400°C, 500°C, and 562°C, respectively, for times up to 300 minutes.…”

Section: Resultsmentioning

confidence: 99%

Effects of Thermal Exposure and Test Temperature on Structure Evolution and Hardness/Viscosity of an Iron-Based Metallic Glass

Nouri

Liu

Lewandowski

2008

Metall Mater Trans A

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High-temperature microhardness testing on drop-cast ingots of fully amorphous Fe 48 Mo 14-Cr 15 Y 2 C 15 B 6 was performed in order to determine the behavior and structure evolution of this Fe-bulk metallic glass under a variety of different test conditions. The effects of changes in test temperature on the microhardness/strength were determined over the temperature range from room temperature to 620°C. Although high (e.g., >12 GPa) microhardness was exhibited at room temperature, significant hardness reductions were exhibited near T g . In addition, the effect of exposure time (up to 300 minutes) at elevated temperature on the evolution of microhardness/strength was also evaluated for selected temperatures between 25°C and 620°C. The microhardness results were complemented with X-ray diffraction (XRD), conventional transmission electron microscopy (TEM), and an in-situ heating TEM study in order to evaluate any structural evolution that could explain the large differences in hardness evolution under different test conditions.

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Section: Resultsmentioning

confidence: 99%

Effects of Thermal Exposure and Test Temperature on Structure Evolution and Hardness/Viscosity of an Iron-Based Metallic Glass

Nouri

Liu

Lewandowski

2008

Metall Mater Trans A

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“…The solute-enriched glassy matrix caused by precipitation of pure a-Al particles also may result in an increase in microhardness. The changes in solute concentration after annealing were estimated from the volume fraction of a-Al obtained according to XRD analysis in the manner previously used by Wesseling et al [16] as shown in Figure 8, assuming the rejected solute is distributed homogeneously in the amorphous matrix. The results show that the microhardness depends linearly on the solute concentration in the matrix, suggesting that the enrichment of solute is more likely the main strengthening mechanism, as proposed in previous reports, [16,17] and is consistent with the effects of the chemistry changes on the hardness changes in the amorphous ribbons, also shown in Figure 8.…”

Section: Discussionmentioning

confidence: 99%

Effects of Changes in Chemistry and Testing Temperature on Mechanical Behavior of Al-Based Amorphous Alloy Ribbons

Huang

Lewandowski

2010

Metall Mater Trans A

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The effects of changes in composition, testing temperature, strain rate, and thermal exposure on the flow behavior of a series of Al-Gd-Ni-X amorphous alloy ribbons have been determined via hot microhardness and tension testing. It is shown that the addition of Fe, Co, and Fe/Co combination into these materials increases the strength, T g , and T x1 in addition to the activation energy for crystallization, whereas the window between T g and T x1 remains similar. The uniaxial tensile tests show these ribbons exhibit a high strength, around 1 GPa, at room temperature (RT), and the results also show that these ribbons maintain their strength, nearly 45 pct of their RT value, at temperatures near T g . Scanning electron microscopy images of fracture surfaces obtained from tests conducted near T g illustrate ductile rupture and homogeneous flow behavior near the fracture tip.

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“…There are also experimental evidence which show increase in the pressure sensitivity with increasing temperature cf. Wesseling et al (2008). 6 The values for the material parameters fs n2 ; s n3 ; f f ; n Ã ; k s; s Ã g can be more accurately determined by fitting it to the stress-strain curves along with the free volume evolution data during plastic deformation.…”

Section: Experimental Procedures and Finite-element Simulationsmentioning

confidence: 99%

The multi-axial deformation behavior of bulk metallic glasses at high homologous temperatures

Ekambaram¹,

Thamburaja²,

Yang³

et al. 2010

International Journal of Solids and Structures

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a b s t r a c tIn this work, we study the behavior of a recently-developed Lanthanum-based bulk metallic glass under uniaxial and multi-axial stress-states using the constitutive model developed by Thamburaja and Ekambaram (2007). The material parameters in the constitutive model are fitted to match the stressstrain responses obtained from a set of simple compression experiments conducted at temperatures within the supercooled liquid region under a variety of strain rates spanning approximately three decades. With the material parameters calibrated, we show that the aforementioned constitutive model is able to accurately predict the force vs. displacement responses of representative experiments conducted under multi-axial stress-states at temperatures within the supercooled liquid region, namely three-point bending and the superplastic forming of a miniature gear component. In particular, the evolution of the specimen geometry during the deformation under multi-axial loading conditions are also well-predicted by the constitutive model.

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Effects of Annealing and Pressure on Devitrification and Mechanical Properties of Amorphous Al87Ni7Gd6

Cited by 18 publications

References 24 publications

Effects of Thermal Exposure and Test Temperature on Structure Evolution and Hardness/Viscosity of an Iron-Based Metallic Glass

Effects of Thermal Exposure and Test Temperature on Structure Evolution and Hardness/Viscosity of an Iron-Based Metallic Glass

Effects of Changes in Chemistry and Testing Temperature on Mechanical Behavior of Al-Based Amorphous Alloy Ribbons

The multi-axial deformation behavior of bulk metallic glasses at high homologous temperatures

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