L Journal of Alloys and Compounds 312 (2000) 130–134 www.elsevier.com / locate / jallcom Resistometric evidence of short-range order formation in the ternary Au Ag Pd alloy 40 40 20 a, b * A.B. Ziya , T. Abbas a Department of Physics, Bahauddin Zakariya University, Multan-60800, Pakistan b Department of Materials Science, Bahauddin Zakariya University, Multan-60800, Pakistan Received 3 December 1999; accepted 16 June 2000 Abstract Short-range order (SRO)-induced electrical resistivity changes were measured in the Au Ag Pd (at.%) alloy during isochronal 40 40 20 annealing experiments. Isochronal annealing after quenching from high temperatures showed that SRO-formation in these alloys leads to 21 an increase in electrical resistivity. From the observation of linearity in the resistivity versus T curves and from a comparison with a theory, it is concluded that the resistivity changes in these alloys are proportional to the changes of the effective SRO-parameter for the first co-ordination shell.  2000 Elsevier Science B.V. All rights reserved. Keywords: Ag–Au–Pd alloys; Isochronal annealing; Electrical resistivity; Short-range order; Vacancies 1. Introduction compared the results with the theory of Yu [1,2]. The results of these investigations are presented in this paper. Direct determination of SRO in the ternary alloys of Au, Ag and Pd by X-ray or neutron scattering has not been reported yet [1,2]. Naidu and Houska [3] considered SRO 2. Experimental details to be a possible mechanism in the unusually large degree of solid solution strengthening of ternary Au–Ag–Pd The details of the annealing and quenching apparatus alloys. As the presence of SRO in concentrated binary used in this study have been described in Ref. [11]. The alloys of Au, Ag and Pd has been already established alloy under investigation was kindly supplied by Degussa [4–6]; therefore, it is reasonable to assume its existence in (Hanau) in the form of an ingot. The given purity of the the concentrated ternary Au–Ag–Pd alloys, but it is to be alloy materials was 99.999%. The chemical composition of noted that the interatomic correlations in ternary alloys the alloy determined by X-ray fluorescence was nearly cannot simply be predicted from the behaviour of atoms in Au Ag Pd . 40 40 20 the binary systems as observed in other ternary alloys like Cu–Ni–Zn, Ni–Re–Mo and Fe–Cr–Ni alloys [7–9]. Also, 2.1. Sample preparation there is no experimental evidence of the presence of long range order (LRO) in these alloys [10]. The following thermo-mechanical treatments were car- Electrical resistivity measurement technique is accurate ried out on this alloy to reduce its thickness from 3 to 0.05 and sensitive for observing microstructural changes. Re- mm. cently, Yu [1,2] developed a theoretical relationship be- Homogenisation at 1273 K for 6 h and intermediate tween SRO-parameters and the electrical resistivity with annealing at 1023 K thrice for 15-min each in vacuum 25 temperature of multicomponent alloys that enabled the use better than 10 mbar. The alloy was quenched in cold of electrical resistivity as an indicator for the degree of water after each heat treatment and subsequently cold SRO. We have used the electrical resistivity measurement rolled. X-ray microanalysis revealed that homogeneity technique to investigate the relationship between SRO and variation of the alloy was ,1 at.%. the electrical resistivity in ternary Au–Ag–Pd alloys and From the resulting 0.05-mm thick bands, samples of dimensions 7532.530.05 mm were cut with the help of a *Corresponding author. foil cutter. In the middle of the sample, a 0.2-mm thick 0925-8388 / 00 / $ – see front matter  2000 Elsevier Science B.V. All rights reserved. PII: S0925-8388(00)01096-3