NANOSTRUCTURED BERYLLIUM-CARBON AND BERYLLIUM-WOLFRAM ALLOYS AND METHOD FOR PREPARING THE SAME

The invention relates to the preparation of nanostructured Be-C and Be-W alloys, to an experimental simultaneous deposition installation and to a process of deposition of thin composite films of said alloys, based on the thermionic vacuum arc method, by a process of physical deposition through ionized vapours, the alloy films being employed to prevent the retention of the fuel used for the fusion reaction in the nuclear reactors. According to the invention, the alloys consist of mixtures of pure phases of Be, W and C and at least one phase of BeW, in case of Be-W alloy, and one phase of BC, in case of the Be-C alloy, and are nanostructured, having a particle size in the range of 10 nm. According to the invention, the installation comprises two high-voltage D.C. generators (1 and 14), two bleeder resistors (2 and 13), two anodes (3 and 12), two focusing cylinders (4) of the Wehnelt type, an anode bar (5) made of W or C having a diameter of 10 mm and a length of 150 mm, a weighing nacelle (11) made of TiBefilled of Be powder (10), two circular cathodes (6 and 9) made of W wire having a diameter of 1 mm, a sample support (8) and two quartz micro-balances (16 and 17). The process claimed by the invention consists in heating the upper part of the W bar (5) and the Be powder (10) in the nacelle (11) by applying an alternating voltage to the W cathodes (6 and 9) followed by applying a high voltage between the W anode (5) and the corresponding cathode, until an electrical discharge controlled by the electron beam emitted by the cathode occurs, after which a similar operation is applied to the Be evaporator, the process parameters are so regulated that the deposition rates are 0.05 nm/s for W and 1 nm/s for Be, the total thickess of the deposited composite film being 200 nm. Invenţia se referă la obţinerea unor aliaje nanostructurate de Be-C, Be-W, la o instalaţie experimentală de depunere simultană şi la un procedeu de depunere a unor filme compozite subţiri din aceste aliaje, bazat pe metoda arcului termoionic în vid, printr-un proces de depunere fizică prin vapori ionizaţi, filmele de aliaj fiind folosite pentru a împiedica retenţia combustibilului utilizat pentru reacţia de fuziune din reactoarele nucleare. Aliajele conform invenţiei sunt constituite din amestecuri de faze pure de Be, W, C şi din cel puţin o fază BeW, în cazul aliajului Be-W, şi o fază BeC, în cazul aliajului Be-C, şi sunt nanostructurate, având dimensiunea particulelor de ordinul a 10 nm. Inst