A New Approach to Estimation of the Thermal Conductivity of Titanium Alloys
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EAL STRUCTURE OF CRYSTALS
A New Approach to Estimation of the Thermal Conductivity of Titanium Alloys M. S. Kalienkoa,b,*, A. V. Zhelninaa, A. V. Volkova, M. O. Ledera, N. A. Tolstykhc, and A. I. Bocharovc a PSC
VSMPO-AVISMA Corporation, Verkhnaya Salda, Russia b Ural Federal University, Ekaterinburg, Russia c Voronezh State Technical University, Voronezh, Russia *e-mail: [email protected]
Received May 24, 2020; revised June 3, 2020; accepted June 3, 2020
Abstract—The thermal conductivities of seven titanium alloys (VT1-0, VT18U, VT20, IMI834, Ti6242S, Ti6Al4V, and Ti6Al7Nb) have been measured. According to the data obtained, the room-temperature thermal conductivity of the investigated alloys varies from 6.4 to 7 W/(m K). A comparative analysis of the influence of alloying elements on the electronic structure and lattice parameters of the alloys has been performed. It is established that the thermal conductivity of titanium alloys increases with an increase in the atomic radius difference ∆r of the alloy (unit-cell volume) and with an increase in the average electron-to-atom ratio (e/a). DOI: 10.1134/S1063774520060176
INTRODUCTION The progress in the development of high-temperature heat-resistant alloys resulted in the design and production of modern turbojet engines. Since the invention of turbojet engines, each new model exhibited an increase in the power and working temperature of the turbine cascades [1, 2]. Therefore, the thermophysical properties of materials are extremely important for further development of propulsion engineering. When designing a turbine engine and an engine exhaust system, an important problem is to provide a desired temperature state of the system elements [3]; to this end, 3D simulation methods based on finiteelement models are currently widely used [4]. Construction of models requires data on the thermophysical parameters of materials (thermal conductivity and specific heat). In addition, a further advance in titanium alloys and improvement of their operating characteristics call for gaining a deeper insight into the relationship between the thermophysical characteristics of materials and their structures and chemical compositions. Titanium alloys have been widely applied in propulsion engineering for more than 50 years and take the second place (after nickel alloys) in the mass composition of the materials used for production of turbojet engines. Titanium alloys are applied to fabricate disks, rings, blades, and elements of engine exhaust system [5, 6]. It is well known that the thermal conductivity of titanium alloys is affected by the following factors: dissolved atoms, intermetallic compounds, grain boundaries, dislocations, temperature, etc. However, to the best of our knowledge, there
have been no publications on analysis of the thermal conductivity and comparative study of the complex influence of alloying elements on the thermal conductivity of titanium alloys. The first results on estimating the thermal conductivity of titanium were reported in 1951 [7]; according to those
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