Abstract: A method is described for the preparation of superconductor massive bodies of MgB2, having a density close to the theorical value, which comprises the following passages: mechanical activation of crystalline boron with the formation of activated powders; formation of a porous preform of said powders; assembly of the porous boron preform and massive precursors of metallic magnesium in a container and sealing thereof in an atmosphere of inert gas or with a low oxygen content; thermal treatment of the boron and magnesium as assembled above, at a temperature higher than 700° C. for a time greater than 30 minutes, with the consequent percolation of the magnesium, in liquid phase, through the activated crystalline boron powders.

Abstract: A method is described for the production of superconductive wires based on hollow filaments made of MgB2, which comprises: a) the formation of a composite billet by means of the coaxial insertion in a tubular metallic container of a cylindrical bar made of metallic magnesium and amorphous boron powder in the interspace between the container and bar, said powder being pressed between the metallic container and the magnesium bar, in such a quantity that the weight ratio magnesium/boron is higher than 1.2; b) at least one plastic deformation treatment of the composite billet thus obtained until a wire with a pre-fixed diameter is obtained, with the subsequent winding of the wire onto a support; c) a thermal treatment of the filament product thus obtained, at a temperature ranging from 700° C. to 950° C. for a time ranging from 15 minutes to three hours.

Abstract: A method is described for the production of superconductive wires based on hollow filaments made of MgB2, which comprises: a) the formation of a composite billet by means of the coaxial insertion in a tubular metallic container of a cylindrical bar made of metallic magnesium and amorphous boron powder in the interspace between the container and bar, said powder being pressed between the metallic container and the magnesium bar, in such a quantity that the weight ratio magnesium/boron is higher than 1.2; b) at least one plastic deformation treatment of the composite billet thus obtained until a wire with a prefixed diameter is obtained, with the subsequent winding of the wire onto a support; c) a thermal treatment of the filament product thus obtained, at a temperature ranging from 700° C. to 950° C. for a time ranging from 15 minutes to three hours.

Abstract: A method is described for the preparation of superconductor massive bodies of MgB2, having a density close to the theorical value, which comprises the following passages: mechanical activation of crystalline boron with the formation of activated powders; formation of a porous preform of said powders; assembly of the porous boron preform and massive precursors of metallic magnesium in a container and sealing thereof in an atmosphere of inert gas or with a low oxygen content; thermal treatment of the boron and magnesium as assembled above, at a temperature higher than 700° C. for a time greater than 30 minutes, with the consequent percolation of the magnesium, in liquid phase, through the activated crystalline boron powders.

Abstract: A method is described for the production of superconductive wires based on hollow filaments made of MgB2, which comprises: a) the formation of a composite billet by means of the coaxial insertion in a tubular metallic container of a cylindrical bar made of metallic magnesium and amorphous boron powder in the interspace between the container and bar, said powder being pressed between the metallic container and the magnesium bar, in such a quantity that the weight ratio magnesium/boron is higher than 1.2; b) at least one plastic deformation treatment of the composite billet thus obtained until a wire with a pre-fixed diameter is obtained, with the subsequent winding of the wire onto a support; c) a thermal treatment of the filament product thus obtained, at a temperature ranging from 700° C. to 950° C. for a time ranging from 15 minutes to three hours.

Abstract: A description follows of an article based on a nickel-chromium-silicon metal alloy, including microcrystalline borides, obtained by the rapid solidification and subsequent thermal treatment of a nickel-chromium-boron-silicon metal alloy comprising from 39.0 to 69.4 atom % of nickel, from 11.8 to 33.9 atom % of chromium, from 7.6 to 27.4 atom % of boron and from 7.6 to 17.5 atom % of silicon. The above article is preferably a tape or a sheet or a fiber having high mechanical properties and is particularly resistant to oxidation.

Abstract: A new copper-based metallic alloy is described containing principally Zn and Al in quantities such as to render it capable, after solution heat treatment at high temperature, and tempering, of assuming a crystalline structure of Beta type; its principal characteristics lies in the fact that it simultaneously contains, as grain size reducing additives, Nb and Ti in an overall quantity lying between 0.01 and 0.2% by weight.

Abstract: A process is described for the production of superconducting conductors of the type comprising a plurality of filaments of an alloy containing niobium and titanium as base materials and a composite matrix of copper, aluminium or alloys of these elements, in which the filaments are disposed, and which serves to stabilize the superconductor; the process includes at least a first phase of preparing a first superconducting conductor comprising:the said filaments and a first matrix of copper, aluminum or alloys of these elements;a second phase of preparing a strip of copper, aluminum or alloys of these elements of width substantially equal to the perimeter of the section of the said first superconducting conductor;a third phase of depositing a layer of brazing material on the outer surface of the said first superconducting conductor and at least on one of the surfaces of the said strip;a fourth phase of connecting the said first superconducting conductor with the said strip and for shaping the strip itself by plas

Abstract: A process for the production of superconductor wires or cables of Nb.sub.3 Al which consists in superimposing sheets of Nb to sheets of Al, inserting the superimposed sheets in a copper container, subjecting the copper container with the sheets contained therein to a plastic deformation processing so as to obtain a reduction in the thickness of the Al sheet to a value of less than about 1.5.mu.m and finally subjecting this product to heat treatment at a temperature between 800.degree. and 1000.degree. C.