Material properties of copper alloys containing arsenic, antimony, and bismuth The material of Early Bronze Age ingot torques Von der Fakultät für Werkstoffwissenschaft und Werkstofftechnologie der Technischen Universität Bergakademie Freiberg genehmigte DISSERTATION zur Erlangung des akademischen Grades Doktor-Ingenieur Dr.-Ing. vorgelegt von Dipl.-Ing. Margrit Junk geboren am 17.01.1973 in Dresden Gutachter.: Prof. Dr. Ernst Pernicka, Freiberg Prof. Dr. Horst Biermann, Freiberg Dr. Peter Northover, Oxford Tag der Verleihung: 16.05.2003 II III Acknowledgements I would like to thank Prof. Ernst Pernicka for the possibility to work on this project and for his support. For providing archaeological material I am grateful to Dr. Stephan Möslein (Bad Tölz), Dr. Hans-Peter Uenze (Prähistorische Staatssammlung München), Werner Haber- länder (Neuhaus b. Schliersee), Dr. Rüdiger Krause (Landesdenkmalamt Baden-Württem- berg, Stuttgart) and Dr. Oldrich Kotyza (Okresní vlastivedné muzeum Litomerice).ˇ The sampling and restoration of the ingot torques and fragments was carried out by the au- thor in the restoration workshop of the Staatlicher Mathematisch-Physikalischer Salon Dresden. For their support and hints I would like to thank Andreas Holfert, Lothar Has- selmeyer and Johannes Eulitz. The copper for the reference material was provided by the Institut für NE-Metallurgie, arsenic by the faculty for chemistry and physics and by Freiberger Compound Materials GmbH. Antimony and bismuth were provided by the Institut für Gießereitechnik. The sand moulds were made by ACTech (Advanced Casting Technologies), Freiberg. The pattern for the mould was provided by the Institut für Gießereitechnik (Dr. Klaus Peukert, Reiner Rabe). The graphite mould was made in the mechanical workshop of the faculty for material science, as well as the specimens for material testing. The reference material was cast by Dr. Hans-Peter Heller, Peter Neuhold and Günter Franke in the Institut für Stahltechnologie. For X-raying the cast rods and for carrying out the tensile tests I would like to thank Reinald Weber (Institut für Werkstofftechnik). The notched bar impact tests were carried out by Dr. Peter Trubitz (Institut für Werkstofftechnik) and Dr. Andreas Weiß (Institut für Stahltechnologie), the torsion tests by Dr. Marlene Spittel, Dr. Werner Jungnickel, and Dagmar Schmidt (Institut für Metallformung). The rods were forged by Uwe Heinze (Institut für Metallformung). With the hardness measurements I was supported by Gudrun Bittner (Institut für Werkstofftechnik), with the stereo microscope by Birgit Liebscher (Institut für Werkstofftechnik). The EPMA and SEM investigations were carried out by Dr. Dietrich Heger, Dr. Hartmut Baum, and Brigitte Bleiber (Institut für Metallkunde). I am indebted to Gudrun Wolf (Institut für Metallkunde) for the support in metallographic preparation. The photographs of the artefacts were taken by Peter Müller (Staatlicher Mathematisch- Physikalischer Salon Dresden). The slides were scanned to files by Maik Böhme (Institut für Archäometrie). I would like to thank Amanda Crain and Dr. Daniel Müller (Departement Erdwis- senschaften, ETH Zürich) for language and proof correction of the manuscript. Finally, and most importantly, I am indebted to my husband and my parents for their patience to discuss about the work and for the support in all stages of the project. IV Abstract This work deals with Early Bronze Age ingot torques, their composition, and material properties. The aim was to decide whether and how a choice of materials by composition or properties was possible during the Early Bronze Age. Early Bronze Age ingot torques were analysed and artefacts from several hoard finds and working stages were investigated metallographically. On the basis of these data the production technology was reconstructed. For the determination of mechanical and technological properties, reference alloys were produced and investigated. The production process was simulated by forging experiments. The investigations revealed that ingot torques were produced by a standardised technology, independent of their composition. The results of the material testing show that it is possible to distinguish the composition of the Early Bronze Age alloys by their mechanical and technological properties. ___________________ Die Arbeit befaßt sich mit frühbronzezeitlichen Ösenringbarren, ihrer Zusam- mensetzung und ihren Werkstoffeigenschaften. Es sollte untersucht werden, ob und wie in der Frühbronzezeit eine Materialauswahl auf der Basis von Zusam- mensetzung oder Eigenschaften möglich war. Frühbronzezeitliche Ösenringbarren wurden analysiert und Artefakte unter- schiedlicher Herkunft und Fertigungsstufen metallographisch untersucht. Auf der Grundlage dieser Ergebnisse wurde die Herstellung der Ringe rekonstruiert. Zur Bestimmung der mechanischen und technologischen Eigenschaften wurden Referenzlegierungen hergestellt und untersucht. Der Herstellungsprozeß wurde durch Schmiedeversuche simuliert. Die Untersuchungen ergaben, daß die Ösenringbarren unabhängig von ihrer Zusammensetzung nach einer einheitlichen Technologie hergestellt wurden. Die Ergebnisse der Werkstoffprüfung zeigen, daß eine Unterscheidung frühbronze- zeitlichen Legierungen anhand ihrer mechanischen und technologischen Eigen- schaften möglich ist. VI Contents List of Tables XI List of Figures XIII Symbols and abbreviations XIX 1 Introduction 1 2 Ingot torques and ingot torque metal 3 2.1 An archaeological view on materials . .............. 4 2.1.1 Alloys in prehistory ..................... 4 2.1.2 Estimates for material classification . ....... 5 2.2 Ingot torques ............................ 11 2.2.1 General remarks and typology . .............. 11 2.2.2 Technology . ..................... 13 2.2.3 The material of ingot torques . .............. 13 2.2.4 Archaeological and archaeometallurgical interpretation of ingot torques . ..................... 17 3 The influence of arsenic, antimony, and bismuth on the properties of copper 19 3.1 The influence of arsenic on copper . .............. 19 3.1.1 The copper-arsenic equilibrium phase diagram . 19 3.1.2 Casting properties ..................... 20 3.1.3 Mechanical properties . .............. 22 3.1.4 Working properties ..................... 23 3.2 The influence of antimony on copper . .............. 26 3.2.1 The copper-antimony equilibrium phase diagram . 26 VIII Contents 3.2.2 Casting properties . ................... 26 3.2.3 Mechanical properties ................... 27 3.2.4 Working properties . ................... 28 3.3 The influence of bismuth on copper . ............ 29 3.3.1 The copper-bismuth equilibrium phase diagram . 29 3.3.2 Casting properties . ................... 29 3.3.3 Mechanical properties ................... 29 3.3.4 Working properties . ................... 30 3.4 The combined influence of the alloying elements . ........ 31 3.4.1 Combined influence of arsenic and antimony on copper . 31 3.4.2 The influence of arsenic and antimony on copper contain- ing oxygen . ................... 32 3.4.3 The influence of arsenic and antimony on copper contain- ing bismuth . ................... 33 4 Methods used for sampling, analysis and material testing 35 4.1 Sampling of archaeological material . ............ 35 4.1.1 Drill shavings for X-ray fluorescence analysis . 35 4.1.2 Samples for metallography . ............ 35 4.2 Analysis . .......................... 36 4.2.1 Energy dispersive X-ray fluorescence analysis . 36 4.2.2 Scanning electron microscopy and electron microprobe analysis . .......................... 38 4.3 Metallography . .......................... 39 4.4 Material testing . .......................... 40 4.4.1 Macroscopic X-ray analysis (radiography) . ........ 40 4.4.2 Vickers hardness test . ................... 40 4.4.3 Tensile test . ................... 42 4.4.4 Notched bar impact test . ............ 43 4.4.5 Torsion test . ................... 44 5 X-ray fluorescence analyses of Early Bronze Age ingot torques 47 5.1 Andechs-Erling, Kr. Starnberg ................... 48 5.2 Piding, Kr. Berchtesgadener Land . ............ 48 5.3 Sicharting, Kr. Traunstein . ................... 52 5.4 Staudach-Egerndach, Kr. Traunstein . ............ 52 5.5 Unterwössen, Kr. Traunstein . ................... 55 5.6 Valley, Kr. Miesbach . ................... 56 Contents IX 5.7 Summary . ............................ 59 6 Metallographic investigation of Early Bronze Age ingot torques 61 6.1 Aschering, Kr. Starnberg . ..................... 61 6.1.1 Fragment Asch1 . ..................... 62 6.1.2 Fragment Asch2 . ..................... 65 6.2 Bernhaupten, Kr. Traunstein . .............. 67 6.2.1 Fragment Ber1 . ..................... 68 6.2.2 Fragment Ber3 . ..................... 68 6.3 Gammersham, Kr. Wasserburg am Inn . .............. 70 6.3.1 Fragment Gam1 . ..................... 72 6.3.2 Fragment Gam2 . ..................... 75 6.4 Hechendorf am Pilsensee, Kr. Starnberg .............. 77 6.4.1 Fragment Hech1 . ..................... 77 6.4.2 Fragment Hech2 . ..................... 78 6.5 Hohenlinden-Mühlhausen, Kr. Ebersberg . ....... 80 6.5.1 Fragment Hoh1 . ..................... 81 6.6 Mühldorf am Inn, Kr. Mühldorf . .............. 84 6.6.1 Fragment Müh1 . ..................... 84 6.7 Pfedelbach-Untersteinbach, Hohenlohekreis . ....... 86 6.7.1 Ingot torque Pfe10 ..................... 86 6.7.2 Ingot torque Pfe14 ..................... 90 6.8 Radostice, okr. Litomericeˇ ..................... 93 6.8.1 Ingot torque Rad2 ..................... 93 6.8.2 Ingot torque Rad4 ....................