COST 507 Thermophysical Properties of Light Metal Alloys Gra zy na J a ro ma-We i Ia nd Rud iger Bra ndt Gunther Neuer DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. COST 507 Thermophysical Properties of Light Metal Alloys Final Report Grazyna Jaroma-Wei la nd Rudiger Brandt Gunther Neuer Under Contract of BMFT 03K075 ISSN 01 73-6698 ASTE February 1994 IKE 5 - 238 Un iversita t Stu ttgart ABSTRACT The thermophysical properties of AI-,Mg- and Ti-based light m studied by reviewing the literature published so far, evaluatin and by empirical investigations. The properties to be covered in are: thermal conductivity, thermal diffusivity, specific heat capacity, thermal expansion and electrical resistivity. The data have been stored in the factual data base THERSYST together with the results of experimental measurements supplied from participants of the COST 507 - action (Group D). Altogether 1325 data-sets referring to 146 alloys have been stored. They have been uniformly represented and critically analyzed by means of the THERSYST program moduli. These numerical data cover a number of systems with variing and thermal treatment. Partly large discrepancies especi conductivity have been found for similar alloyflry often the in corresponding publications are not complete enough to identify whether such discrepancies can be explained by other material related characteristics, such as thermal pretreatment etc. or whether experimental reasons are responsible. Therefore additional measurements are necessary in order to enable reliable statements upon variation of thermophysical properties (especially thermal conductivity) with chemical composition and microstructure. The aluminium based alloys are very good heat conductors with thermal conductivities in the range between 70 Wm-'K' and 170 Wm%'. At measurements of thermal conductivity under steady-state condition a high heat flux has to be duced in the sample. This fact causes many difficulties during measurementsxe problem experimental ainties has been studied in detail by investigation of AA-8090 (AI-2.5Li-1.1 a number of experimental improvements could be realized. The data has been tested by comparative measurements of the same material with different measuring techniques in several laboratories. A low disagreement of 6% at room temperature and 4.5% at 200°C has been found. 7 The thermophysical properties (~een~udi~i~~~~r~~~i~sivity,Specifie-Reat- -eapaeity] of monolithic alloy KS1275 (AISil2CuNi) and metal matrix composite @ n,b (KS1275 reinforced with A,O, short fibre) have been determined experimentalld Thermal conductivity data have been used to apply theoretical models to describe the thermal conductivity of two-phase composites as a function of geometry and volume content of the components. Foreword This study of the "Thermophysical Properties of Light Metal Alloys" was sponsored as Project No. 03K075 by the Bundesministerium fijr Forschung und Technologie (BMFI). We wish to thank Kolbenschmidt AG (Neckarsulm, FRG) and Vereinigte Aluminium Werke (Bonn, FRG) for supplying the specimens to be studied. We express our thanks to the partners of COST507 action for good cooperation. Especially the contributions by A-M. Zahra (CNRS Marseille, France), W. Lacom (ARC Seibersdorf, Austria) and F. Richter (Muhlheim, FRG) have been important. Also the participation of L. Binkele (EA Julich, FRG) at the comparative measurement programme was very helpful. Finally we are grateful to Prof. P.G. Klemens (University of Connecticut, Storrs, USA) for fruitful discussions about the theoretical modeling of the thermal conductivity of alloys. Contents 1. Aim of the study 2. THERSYST data base 3. Storage of thermophysical properties of light metal alloys in THERSYST 3.1 Literature sources 3.2 Transfer of the data from the COST partners 3.3 Thermophysical property data 4. Experimental investigations 4.1 Measurement methods 4.2 Materials to be studied 4.3 Measurements of thermal conductivity of good heat conductors by steady-state method 4.4 Comparative measurements on A48090 alloy 4.5 Thermophysical properties of metal matrix composite (KS1275/AI2O3-fibre) 5. Theoretical analysis of the thermal conductivity of metal matrix composites. 5.1 Models for the effective thermal conductivity of two-phase materials 5.2 Comparison of calculated and measured thermal conductivity data 6. Conclusion 7. References Appendix A: List of evaluated literature B: List of materials and properties stored in THERSYST 1 1. Aim of the study The rapid increase in the application of light metal alloys in the aerospace, automobile and transport industry, as well as in energy technique caused a great interest in thermophysical properties of these materials. Many light-metal-basedcomponents are exposed sometimes to temperatures up to 400°C, resulting in the generation of stationary or transient temperature fields. The knowledge of thermal transport properties enables the calculation of these temperature distributions and therewith predictions of chemical reaction and thermo-mechanical stresses of thermally loaded components resulting in creep, destructure, etc. Therefore it was decided to study the thermophysical properties of AI-,Mg- and Ti-based alloys in frame of the programme COST-507. Is is well known that the thermophysical properties and especially the thermal conductivity of solids not only depend on chemical composition but also on chemical and thermal pretreatment of the material resulting in a variation of the micro- or macrostructure. The first aim of the study therefore was to critically analyse the literature with respect to available data and to relations between thermophysical properties and material characterization. The measurement of thermal conductivity of high conductive metals are very difficult and it was a second aim of the study to improve existing measurement equipment in order to achieve higher accuracies and reliabilities of measurements of such materials. The availability of a number of laboratories in the frame of COST507 could be advantageously used to compare different measurements techniques and to test the reliability of the results. Metal matrix components, which have been developed to improve mechanical properties of light metals, should be investigated experimentally because nearly no literature is available upon such materials until now. The experimental programme has been planned in order to find correlations between the thermal conductivity of a composite and the data of its components. Finally all data - the literature data and the experimental results of all COST507 laboratories have been made available by means of the data base THERSYST. The properties to be covered were: thermal conducljvity, thermal diffusivity, specific heat capacity, thermal expansion and electrical resistivity. 2 2. THERSYST - data base There are three data bases which deal with thermophysical properties of solid materials. The comprehensive data base system at CINDAS (West Laffayette, USA) covers all thermophysical properties for many groups of specific materials, such as dielectric materials, composite materials, high temperature materials, aerospace structural materials, etc [l].But these data are only accecible for limited groups of users and any cooperation with foreign partners is not possible. The thermal conductivity data base in Japan [2] deals with certified reference materials, candidates for reference materials, and other well-characterized materials. Other thermophysical properties (specific heat capacity, electrical resistivity, thermal expansion, and emissivity) are registered as supplemental properties only. ALUSELECT data base [3] has been developed to offer so-called harmonized values for aluminium and aluminium alloys, which can be further improved by the European Aluminium Association as the EAA official data. Data from the open literature, from the handbooks and from sheets of manufactures have been collected in the data bank but only evaluated values are accesible. THERSYST database has been developed as a combination of a factual database for thermophysical of properties solids and a modular program system to handle the database content. The advantage of such a system is that program components can be added or deleted in a relatively easy manner to permit an optimum configuration. As thermophysid properties are depending on material parameters and experimental conditions (meta-data), the information of all factors of influence should be stored in the data-base and the original context between the intrinsic properties data and meta- data should be preserved. This problem has been solved in THERSYST using the class concept [4]. The physical information is converted into a standardized form given by the THERSYST scheme of category and it is stored in the form of data-sets. The scheme of category is separated into five classes: class 1, material designation, class 2, material characterization, class 3, experiment description, class 4, thermophysical property data and class 5, bibliography. Classes 1 to 4 are hierarchically structured, the class bibliography is linked to the corresponding data-set by a document number (Fig. 1). The information belonging to the data-set is stored in the form of descriptors, which can be numerical, coded or in text form. In Tab. 1 some important material and experiment parameters are listed, which are used in THERSYST as descriptors. It is also indicated, which thermophysical