بررسي ريزساختاري آلياژ باستاني ايراني سه جوش

Investigation of the microstructure of the ancient Iranian Sehjush alloy

در اين مقاله، يك شيء سكه شكل، ساخته‌شده از آلياژ باستاني ايراني سه جوش، مورد مطالعه قرار گرفته است. جهت بررسي ساختاري اين آلياژ، از روش هاي ميكروسكوپي و آناليز شامل متالوگرافي، XRF به منظور آناليز عنصري، XRD به منظور آناليز فازي، ميكروسكوپ الكتروني روبشي(SEM)، EDS و سختي‌سنجي ويكرز استفاده شده است. نتيجه بررسي‌ها نشان مي‌دهد كه اين آلياژ، بر پايه مس است و سرب به صورت ذره‌هاي پراكنده در ساختار و به‌عنوان عنصر آلياژي به آن اضافه شده كه احتمالا با هدف بهبود كارپذيري بوده است. بقيه عناصر يافت‌شده به‌صورت ناهمگن وجود دارند. به‌نظر مي‌رسد به جهت تزيين يا محافظت آلياژ در برابر محيط، سطح شيء تحت پوشش قلع اندود قرار گرفته بوده است. همينطور نتايج سختي‌سنجي‌ها بيانگر آن است كه احتمالا تركيب شيميايي در كل شيء مورد بررسي يك‌دست نبوده و يا تحت تاثير حرارت‌دهي غيريكنواخت قرار گرفته است.

The metallurgical industry has been popular in Iran for a long time and various alloys with different names have been made, especially in the Islamic period in Iran. Unfortunately, there is insufficient metallurgical knowledge of many of these alloys and their composition, microstructure and properties remain unknown. The use of new analysis and testing tools used in materials engineering can help to identify these ancient alloys and understanding the nature and method of their construction. In this paper, a coin-shaped object made of three-weld alloy is studied. For structural analysis of this alloy, microscopic and microanalysis methods including metallography, XRF for elemental analysis, XRD for phase analysis, scanning electron microscopy (SEM), scanning electron microscopy combined with energy dispersive X-ray spectroscopy (SEM-EDS) and Vickers micro hardness test have been used. The results show that this alloy is based on copper and lead has been added as an alloying element. Lead is present in the form of dispersed particles in the structure and was probably added to improve workability. The other elements found are heterogeneous and it cannot be concluded that these elements have been used as alloying elements in this alloy. The surface of the object appears to be tin-plated to decorate or protect the alloy against the environment. Also, the results of hardness tests indicate that the chemical composition of the whole object may not be uniform or may have been affected by non-uniform heating.