Title: Effect of rare-earth atomic radius on the devitrification of Al<sub>88</sub>RE<sub>8</sub>Ni<sub>4</sub>amorphous alloys
Abstract: Abstract To find a suitable Al-rich (>80 at.%) Al—RE—TM (RE = rare-earth, TM = transition metal) amorphous alloy for nucleation and growth studies, a series of Al88(GD1—x Er x )8Ni4 and Al88(La1—x Gd x )8Ni4alloys has been investigated by X-ray powder diffraction (XRD) and differential scanning calorimetry (DSC) measurements. The alloys containing the smaller radius rare-earth atoms (≤ 1.8013 Å, i.e., Al88(Gd1—x Er x )8Ni4 for all x) produce fcc Al nanocrystals on devitrification. However, they do not show a glass transition temperature (T g), although they appear to be amorphous by XRD and show a peak in isothermal DSC during devitrification, characteristics of a transformation by nucleation and growth. By contrast, the alloys containing the larger radius rare-earth atoms (≥1.811 Å) show a well-defined T g and a peak in isothermal DSC, characteristics of a true amorphous alloy. However, only over a limited radius range (1.811 Å ≤ average rare-earth radius ≤ 1.821 A, corresponding to Al88La1Gd7Ni4 and Al88La2Gd6Ni4, respectively), do they produce fcc Al nanocrystals; for the larger radius rare-earth atoms. metastable intermetallic phases are formed. These results demonstrate an unambiguous correlation between the average rare-earth atomic radius, glass formation, and the devitrification behaviour of Al—RE—TM alloys.
Publication Year: 2000
Publication Date: 2000-05-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 68
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