TEM Analysis of Short Range Ordering in Amorphous Materials
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Figure 1697a shows a HRTEM and electron diffraction pattern of a thermally quenched  Zr70Al8Cu13.5Ni8.5 MG (metallic glass).  The diffraction pattern shows a diffusion halo, indicating the absence of precipitates with size larger than 3 nm. Moreover, the absence of any nanocrystalline phase in the diffraction pattern confirms that this material consists of only a purely glassy structure in amorphous phase. The HRTEM image further showing a highly disordered structure without any sign of nanocrystals or ordered clusters, confirms again the fully glass nature.

HRTEM and its electron diffraction pattern of an as-cast Zr70Al8Cu13.5Ni8.5 MG (metallic glass)

Figure 1697a. HRTEM and electron diffraction pattern of a thermally quenched  Zr70Al8Cu13.5Ni8.5 metallic glass. [7]

The method based on FFT and inverse FFT developed by Miller and Gibson [2] and extended by Li et al. [3] and Jiang and Atzmon [4] later was applied to analyze the SRO (short range ordering) clusters by Zhu et al. [1]. They employed a core–shell model to investigate the shear bands in as-cast Zr64Nb6Cu13.5Ni8.5Al8 specimen (Figure 1697b). In Figure 1697b (b), the bright-yellow part represents the zone with more free volume (FV), while the dark-blue part represents the zone with less FV. The core is proposed as SRO clusters with a different coordination number (CN) [5] and the local FV is shell. It is defined that SRO clusters with CN of 12 or more than 12 have no FV, while ordering clusters with CN < 12 have certain FV [6].

fast Fourier transform (FFT) pattern of an as-cast sample for Zr64Nb6Cu13.5Ni8.5Al8 alloys

Figure 1697b. (a) HRTEM image of an as-cast sample for Zr64Nb6Cu13.5Ni8.5Al8 alloys (the inset presents fast Fourier transform (FFT) pattern), and (b) The corresponding Fourier-filtered, threshold filtered and inverted image. Adapted from [1]

 

 

 

 

[1] Z.W. Zhu, L. Gu, G.Q. Xie, W. Zhang, A. Inoue, H.F. Zhang, Z.Q. Hu, Relation between icosahedral short-range ordering and plastic deformation in Zr–Nb–Cu–Ni–Al bulk metallic glasses, Acta Materialia 59 (2011) 2814–2822. 
[2] Peter D. Miller and J. Murray Gibson, Connecting small-angle diffraction with real-space images by quantitative transmission electron microscopy of amorphous thin-Þlms, Ultramicroscopy 74 (1998) 221-235.
[3] Li J, Wang ZL, Hufnagel TC. Phys Rev B 2002;65:144201.
[4] Jiang WH, Atzmon M. Acta Mater 2003;51:4095.
[5] Miracle DB, Sanders WS, Senkov ON. Philos Mag 2003;83:2409.
[6] Liu XJ, Chen GL, Hui XD, Liu CT, Lu ZP. Appl Phys Lett 2008;93:011911.
[7] Y.H. Li, W. Zhang, C. Dong, J.B. Qiang, K. Yubuta, A. Makino, A. Inoue, Unusual compressive plasticity of a centimeter-diameter Zr-based bulk metallic glass with high Zr content, Journal of Alloys and Compounds 504S (2010) S2–S5.

 

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