Influence of Microalloying with Yttrium on the Relaxation Properties of Copper
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INFLUENCE OF MICROALLOYING WITH YTTRIUM ON THE RELAXATION PROPERTIES OF COPPER V. M. Arzhavitin,1,2 B. V. Borts,1 A. F. Vanzha,1 N. D. Rybal’chenko,1 and V. I. Sytin1
UDC 539.67
The influence of microalloying with yttrium on the relaxation properties of copper is investigated. The grain-boundary and “impurity” grain-boundary relaxation peaks of the internal friction are discovered. The energy of binding of yttrium atoms with grain boundaries of copper is determined by measuring the “impurity” grain-boundary internal friction. Keywords: copper microalloyed with yttrium, internal friction, microstructure, energy of binding of yttrium with grain boundaries of copper.
Copper is widely used in various branches of science and engineering and, in particular, in the production of some elements of fusion reactors. As one of the procedures aimed at the improvement of operating and technological characteristics, one can mention its microalloying with (at most 0.1%) chemically active elements characterized by the refining and modifying actions. The researchers of the “Khar’kov Physicotechnical Institute” National Scientific Center developed some copper-based alloys microalloyed with rare-earth metals and, in particular, with yttrium, which proves to be a good modifier refining the structures of the matrices and secondary phases. Yttrium also promotes an additional refining of copper by gaseous and other “detrimental” fusible impurities. The refractory compounds with impurities formed as a result partially float up in the course of crystallization to the surface of the ingot and are removed by the mechanical treatment [1, 2]. As an important mechanism of the influence of small amounts of alloying chemical elements on the properties of metals, one can mention the intercrystalline internal adsorption [3]. Hence, we study the influence of this type of adsorption of yttrium on the relaxation properties of copper on the basis of the results of measurements of internal friction. Materials and Methods We used the specimens made of vacuum-fused copper microalloyed with yttrium. In order to produce these specimens, we took M0k polycrystalline copper with the following chemical composition: up to 0.001 wt.% Fe, Ni, P, As, Pb, Zn, Sb, and Sn, up to 0.002 wt.% S and Ag, at least 99.97 wt.% Cu, and up to 0.015 O and 0.0005 Bi. The procedure of alloying was carried out by using ItM-1 metallic yttrium with concentrations of 0.01, 0.02, and 0.05 wt.% in the course of vacuum inductive melting. The specimens were held at 550°С for 1 h (under a pressure of 10 − 3 Pa ).
1
Institute of Solid-State Physics, Materials Science, and Technologies, “Khar’kov Physicotechnical Institute” National Scientific Center, Ukrainian Academy of Sciences, Kharkov, Ukraine. 2 Corresponding author; e-mail: [email protected]. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 50, No. 3, pp. 97–100, May–June, 2014. Original article submitted April 25, 2013. 1068-820X/14/5003–0421
© 2014
Springer Science+Business Media New York
421
V. M. ARZHAVI
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