ELSEVIER Inrermetallics 6 (1998) 479485 0 1998 Elsevier Science Limited PII: SO966-9795(97)00057-5 Printed in Great Britain. All rights reserved 0966-9795/98/T-see front matter A method for seeking high thermal conductivity compounds Yoshihiro Terada,“” Junji Nakata,” Tetsuo Mohri” & Tomoo Suzuki” zyxwvutsrqponmlkjihgfed aDivision of Materials Science and Engineering, Graduate school of Engineering, Hokkaido University, Kita-ku, Sapporo 060, Japan bKochi University of Technology, Tosayamada, Kochi 782, Japan (Received 14 April 1997; accepted 15 July 1997) Thermal conductivity of an intermetallic compound is characterized as an enhancement due to ordering with reference to the basic contribution of solid solutions. A necessary condition of having high thermal conductivity of a given intermetallic compound is, therefore, that the solid solution itself transports high thermal current. A periodic table in helical form for seeking the high conductivity compound is proposed by summarizing the electrical resistivity data of solid solu- tions. Assessments of thermal conductivity were conducted for the intermetallic compounds based on noble metals. CusAu, CuAu and AgMg show the maximum value for 157, 167 and 147 W m-’ K-’ at ambient temperature among Lls, Lla and B2 compounds, respectively. 0 1998 Elsevier Science Limited. All rights reserved Key words: A. intermetallics, miscellaneous, B. thermal properties, electrical resistance and other electrical properties, G. aero-engine components. 1 INTRODUCTION 2 MODEL FORMULATION Thermal conductivity is an important physical property for elevated temperature structural appli- cations of metallic materials.le3 Rapid heat trans- fer afforded by high thermal conductivity enables efficient cooling, which suppresses the appearance of life limiting heat-attacked spot, resulting in higher operating temperature.4 Also, high thermal conductivity assures uniform temperature distribu- tion, which reduces the thermally-induced stresses and, thereby, improves fatigue properties.5 Thermal conductivity in intermetallic com- pounds has been extensively investigated for sev- eral kinds of AB- and As&type structures.2,“” Yet, a large portion of the works are centered around the organization and systematization of measured data and not many discussions are pro- vided for predicting a compound with high thermal conductivity. Motivated by such a deficiency, the present study is undertaken. The main purpose of the present report is to propose a method of pre- dicting an inter-metallic compound with a high thermal conductivity. The main emphasis of this study is placed on noble metal compounds. *To whom correspondence should be addressed. 479 The dependence of electrical resistivity on the composition is characterized by a convex parabolic curve in some metallic binary continuous solid solutions, typically for isoelectronic alloy sys- tems.12-16 The curve is described satisfactorily by the analytic expression proposed by Nordheim as follows:‘7~18 p=(l -X)~/4+X&?+kX(1-x) (1) where PA and PB are the electrical resistivities of the pure elements A and B, x represents the composi- tion of element B, and k is a positive constant which depends on the alloy system. A typical example of Nordheim’s relation was confirmed by Johansson et al. for a Cu-Au system as shown in Fig 1 i9 In this alloy, the order-disorder transfor- . . mation takes place at some stoichiometries.20 It is noted that the resistivity is decreased by ordering as shown by solid circles in the figure. Nordheim’s relation can be converted to thermal conductivity by using the Wiedemann-Franz rela- tion, which claims that thermal conductivity is inversely proportional to electrical resistivity.21p23 Providing that the Lorentz numbers do not change appreciably for both components and solid