Journal of Alloys and Compounds 391 (2005) 38–41 Effect of cold working on ordering of an equiatomic CuPt alloy Kunihiro Hisatsune ∗ , Takanobu Shiraishi, Yasuko Takuma, Yasuhiro Tanaka, EriMiura Division of Dental and Biomedical Materials Science, Department of Developmental and Reconstructive Medicine, Course of Medical and Dental Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8588, Japan Received 6 June 2004; received in revised form 29 July 2004; accepted 17 August 2004 Abstract Effect of cold working on the ordering of an equiatomic CuPt alloy during continuous heating was studied by means of electrical resistivity measurements, hardness tests, differential scanning calorimetry, and X-ray diffraction. The ordering after cold working occurred in three stages with remarkable acceleration, namely, the migration and the annihilation of excess vacancies (I a ), those of secondary defects (I b ) and the migration of equilibrium vacancies (II) as well as that of quenched sample. The lattice defects introduced by cold working advanced the stages I a and I b , and therefore decreased the stage II. There existed two temperature regions with softening due to ordering enhanced recrystallization and normal recrystallization. © 2004 Elsevier B.V. All rights reserved. Keywords: Intermetallics; Metals; Point defects; X-ray diffraction; Calorimetry; Ordering; Cold working 1. Introduction It is well known in CuPt [1,2], Ni 3 Al [3], FeCo [4] and so on that the ordered state is destroyed by cold working. Be- cause cold working introduces many lattice defects in alloys and makes some confusion on atomic arrangement. Effects of cold working on ordering have been studied in many al- loys. Johnes and Sykes [5], Roessler et al. [6] and Mitsui et al. [7] have reported that the orderings are retarded by cold working. On the other hand, Arunachalam and Cahn [8], Ward and Mikkola [9], Feller-Kniepmeier and Ruckert [10], Buckley [4] and Blackford et al. [11] have concluded that subsequent annealing after cold working accelerates the ordering. However, their discussions are not concentrated in the reaction rate of disorder to order but that of antiphase domain (APD) growth. The APD growth may correspond to relatively later stage of ordering processes. Few studies have been known of effects of cold working on the early stage of ordering. Though the ordering process in CuPt has been studied by many researchers [12–18], no study has been done about the ∗ Corresponding author. Tel.: +81 95 849 7656; fax: +81 95 849 7658. E-mail address: hisatune@net.nagasaki-u.ac.jp (K. Hisatsune). effect of cold working on it. The object of the present work is to clarify the effects of cold working on the ordering of a disordered CuPt alloy during continuous heating. 2. Experimental procedures Alloy was prepared by vacuum melting together 99.95 wt.% Pt and 99.99 wt.% Cu. The chemical analysis of the alloy showed 50.63 at.% Pt as compared to 50 at.% Pt for stoichiometric CuPt. We finally obtained a homogeneous wire specimen 1 mm in diameter by alternative annealing and drawing. The alloy was disordered at 1223 K for 1800 s and then quenched into ice brine. Subsequently it was cold-rolled to various reductions in thickness. Thereafter, they were contin- uously annealed from room temperature to 1223 K at various heating rates, namely anisothermal annealing. The effect of cold working on the ordering of CuPt was investigated by means of electrical resistivity measurements, hardness tests, differential scanning calorimetry (DSC) and X-ray diffrac- tion (XRD). The electrical resistivity measurements were made in vac- uum using a four-terminal potentiometric apparatus. The 0925-8388/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2004.08.022