Dani János - Hajdú Zsigmond - Nagy Emese Gyöngyvér szerk.: MÓMOSZ I. (Debrecen, 2001)

Szabó Géza: Újabb eredmények és módszerek a Kárpát-medence késő bronzkori tárgyainak archaeometallurgiai vizsgálataiban

needle (No. 80) along characteristic straight lines one could observe split twinned crystallites indicating, that after the annealing it was not processed any more. The prolonged crystallites on the flattened head, however, clearly show processing after the annealing of this part. It is a frequent collateral effect with the annealed objects, that a characteristic tin-rich segregation is formed along the crystallite boundaries covering in a netlike manner nearly the whole surface. /Fig. 5., 4./ At the articles which were annealed after working, the strain annealing process is indicated by the split twinned crystallites appearing along straight lines and observable on the cut surfaces. Efficiency of the homogenisation, as it can be concluded observing the cuts, is rather various. E.g. on a saw-blade (No. 63) with a magnification of 400 sporadic and distant distribution of twinned crystallites indicate that the recrystallisation was not complete during the annealing, homogeneous alpha texture was not obtained. Due to the rather low temperature and its short period, a soft half-product was produced suitable to further processing. It was very important in the case of bronze pins. The texture, characteristic for bronze pins can fairly be traced on a polished surface of a wire spiral fragment (No. 130). At a magnification of 400 one can clearly see the twinned crystallites along straight lines, and at the edge a yellowish layer of different structure abundant with tin. The twinned crystallites with sizes changing between 40 to 100 micron indicate a relatively soft material suitable to further processing. In a case of a melted fibula the fact, that the boundary of twinned crystallites, in spite of intense later thermal impact, remained slightly wavy, indicates that the recrystallisation was not everywhere complete. This can be attributed presumably to the short-period high temperature annealing followed by fast cooling. This „annealing" was not enough to melt the remainder of the alpha+delta residue between the alpha crystals and to fully soften the material of bronze pin. This process can be observed with other objects, too. In the structure of a cast bronze ring, beside the small polygonal crystallites indicating fast cooling of the mould, several twinned crystallites can also be observed. The pattern of the cut surface shows, that the casting mould was not warmed up or quickly cooling form had been used. The scarcely appearing twinned crystallites probably point to an applied force producing grain strain in the article and this was subject to heat, or the warmed ring was processed. On the outer edge the flattened part of 1,1 cm, bending of the object near the fracture boundary and the fracture edge is thicker and sharper protruding from the original plan of the material; all this indicate the same. The homogenisation, however, should have been very short and at a low temperature, so as the complete rearrangement could not be realised. According to the observed phenomena and the missing piece one can conclude that the cast ring originally was warmed up before cutting, and the missing part was broken away. Particular picture is represented by the cut of the plate-backed fibula (No. 87), which shows a strongly formed prolonged texture, and one can clearly follow also the direction of the extension. This texture in unique in the studied material and it indicates that during manufacturing the bronze pin serving as basic material for the fibula, the usual transformation process was prevented by extraordinary quick water cooling from the beta phase temperature range. The pattern of the alloy on the cuts of studied objects in every case shows a bronze with low tin content along with presence of some metals which can be regarded as impurities. EVALUATION OF STUDIED FINDS BASED ON THE ALLOYING CONTENT Micro-spectrum analyses of the Veravár treasure find performed with roentgen-fluorescence method support the conclusion about the low tin content drawn also from the microscopic patterns. In every case tin content is much below the resolution threshold i.e. 14%, that means at the same time, that the objects were made of alloys suitable to further processing. According to the results of XRF analyses, for most objects, particularly for simpler ones, the tin is present in an order of magnitude of per cent, but one can also see on the curve, that the peak is quite small, mostly below the limit value of 3 to 4 per cent. This observation is supported also by the data of SEM analyses. On can observe little higher values for the tin content, at about 7 per cent in the case of the simple cast ring (No. 90), and, frequently with the objects manufactured from worked, annealed bronze pins, too. The similarity of the problem of relation between the raw material used to manufacture the bronze pins and the ringshaped casts common in the late Bonze Age. For the annealed bronzes one can often observe textures of different structure in the interior and the exterior of the bronze and also near the surface.