Photon Factory Activity Report 2005 #23 Part B (2006)
Materials Science

7C/2004G223

Structural analysis of Pd40Cu40P20 and Pd45.5Cu35.5P19 metallic glasses
Osami HARUYAMA*, Kazumasa SUGIYAMAa, Masatoshi SAITOb and Yoshio WASEDAc*Faculty of Science and Technology, Tokyo University of Science, Noda 278-8510
aEarth and Planetary Science, The University of Tokyo, Bunkyou-ku 113-0033
Faculty of Medicine, Niigata University, Niigata 951-8518
cInstitute for multi-component materials, Tohoku University, Sendai 980-8577

Pd-Cu-P alloy system is a constituent of Pd-Cu-Ni-P
glass system, showing an extremely small critical coolingrate for vitrification and high resistance to crystallization[1]. Another component, Pd-Ni-P ally system has been
examined well about the structure. However, thestructural analysis of Pd-Cu-P glass system has not beenpresented. Although Hi et al. reported [1] that a bulk PdCu-P glass is capable to produce over a large
compositional range, a typical Pd40Cu40P20 glass has notbeen reported to be obtained in a bulk shape. We havecarefully searched an adequate composition for bulk glass
formation and succeeded to produce a bulk glass with thePd45.5Cu35.5P19 composition by water-quenching. Thissuggests that the glass forming ability (GFA) wasremarkably improved by a small adjustment of alloy
composition. The objective in the present report is tocheck the difference of amorphous structure between
Pd40Cu40P20 and Pd45.5Cu35.5P19 glasses.
Experimental Results
A bulk Pd45.5Cu35.5P19 glass with a rod shape of 6 mm indiameter and 20 mm in length was prepared by waterquenching. A ribbon Pd40Cu40P20 glass was prepared bymelt-spinning with a cupper roll. The structural analysis
for these glasses was performed by normal scattering withMo-Kα radiation (17.5 keV) and anomalous X-rayscattering (AXS) experiments near the Cu-K absorption
edge (8.980 keV) with a far-edge energy of 8.680 keV
and a near-edge energy of 8.955 keV at BL7C station.
AXS enables us to examine the species-specified local
structure of the glass, i.e. Cu-P, Cu-Cu and Cu-Pd
correlations
Figure 1 presents the radial distribution functions(RDFs) for AXS-experiments, where the number
densities, 75.3 and 74.1 nm-3, were used for Pd40Cu40P20
and Pd45.5Cu35.5P19 glasses. The 1st peaks of RDFs werefitted well by a linear combination of three Gaussianfunctions, corresponding to the nearest Cu-P, Cu-Cu andCu-Pd atomic correlations. The nearest neighbour
distance rij and coordination number Nij were estimatedand the result is summarized in Table I. The rij isphysically acceptable, when compared to the atomic
radius rPd=0.141, rCu=0.127 and rP=0.100 in ref. [3].
Nearest neighbour metallic atoms Z around the centred Patom, assuming the statistical distribution of the metallic
atoms, is predicted to be Z=1.7x(0.4/0.2)x2≈6.8 for thePd40Cu40P20 glass, and this result is compatible withvarious metal-metalloid binary glasses [4]. The

coordination number of Cu and Pd atoms around thecentred Cu atom, NCuCu and NCuPd, are compatible with eachother for Pd40Cu40P20 glass, while NCuCu is rather larger for
Pd45.5Cu35.5P19 glass than Pd40Cu40P20 glass. Also,NPCu≈3.5x(0.355/0.19)=6.5 is obtained, and this value isapproximatelytwotimes
larger
thanNPCu=1.7x(0.4/0.2)=3.4 of Pd40Cu40P20 glass. When the tricapped triangular prism constitutes a predominant part ofthe local structural unit of a glass with the composition of
TM80M20 (TM: transition metal, M: metalloid) [4], NMTM
should range over 6 – 9. Therefore, under the assumptionthat the local amorphous structure for Pd45.5Cu35.5P19 glass
is similar to that for Pd40Cu40P20 glass, the present results
suggest that micro-phase separative tendency might
increase in Pd45.5Cu35.5P19 glass.
300RDFCU(r) ⁄nm-1

Introduction

Pd45.5Cu35.5P20
Pd40Cu40P20250200
150100AXS50
00.20

0.25

0.30

0.350.40

0.450.50

r /nm

Fig. 1 AXS radial distribution functions. Fine lines show
the de-convolution of 1st peaks due to Gaussian functions.

Pd40
Pd45.5

Cu-P
rij
Nij
0.240
1.7
0.244
3.5

Cu-Cu
rij
Nij
0.259
4.8
0.265
7.8

Cu-Pd
rij
Nij
0.282
5.90.288
3.8

Table I.Comparison of rij and Nij for Pd40 and Pd45.5 glasses.
References[1] N. Nishiyama and A. Inoue: Appl. Phys. Lett. 80,2002, 568.
[2] Y. Hi, T. Shen and R.B. Schwarz: Metall. Mater.
Trans. 29A, 1998, 1795.
[3] T. Egami and Y. Waseda: J. Non-crystal. Solids. 64,1984, 113.
[4] P.H. Gaskell: Glassy Metals II, edited by H.Beck andH.-J. Güntherodt, Springer, 1983, p.5* haruyama@ph.noda.tus.ac.jp

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