A tantalum or tantalum alloy which contains pure or substantially pure tantalum and at least one metal element selected from the group consisting of Ru, Rh, Pd, Os, Jr, Pt, Mo, W and Re to form a tantalum alloy that is resistant to aqueous corrosion. The invention also relates to the process of preparing the tantalum alloy.

A tantalum or tantalum alloy which contains pure or substantially pure tantalum and at least one metal element selected from the group consisting of Ru, Rh, Pd, Os, Jr, Pt, Mo, W and Re to form a tantalum alloy that is resistant to aqueous corrosion. The invention also relates to the process of preparing the tantalum alloy.

Provided is a master alloy for a sputtering target, wherein, when elements constituting the master alloy are following X1, X2, Y1, Y2, Y2, and Y3; specifically, where X1 is one or two types of Ta or W; X2 is at least one type of Ru, Mo, Nb or Hf; Y1 is one or two types of Cr or Mn; Y2 is one or two types of Co or Ni; and Y3 is one or two types of Ti or V, the master alloy comprises any one combination of X1-Y1, X1-Y2, X1-Y3, X2-Y1, and X2-Y2 of the foregoing constituent elements. The present invention consequently yields superior effects of being able to obtain a sintered sputtering target with few defects and having a high-density and uniform alloy composition, and, by using this target, to realize the deposition of an alloy barrier film with uniform quality and few particles at a high speed.

Provided is a master alloy for a sputtering target, wherein, when elements constituting the master alloy are following X1, X2, Y1, Y2, Y2, and Y3; specifically, where X1 is one or two types of Ta or W; X2 is at least one type of Ru, Mo, Nb or Hf; Y1 is one or two types of Cr or Mn; Y2 is one or two types of Co or Ni; and Y3 is one or two types of Ti or V, the master alloy comprises any one combination of X1-Y1, X1-Y2, X1-Y3, X2-Y1, and X2-Y2 of the foregoing constituent elements. The present invention consequently yields superior effects of being able to obtain a sintered sputtering target with few defects and having a high-density and uniform alloy composition, and, by using this target, to realize the deposition of an alloy barrier film with uniform quality and few particles at a high speed.

Methods for producing a multifilament Nb.sub.3Sn superconducting wire having a Jc value of at least 2000 A/mm.sup.2 at 4.2 K and 12 T by a) packing a plurality of Cu encased Nb rods within a first matrix which is surrounded by an intervening Nb diffusion barrier and a second matrix on the other side of the barrier remote from the rods thereby forming a packed subelement for the superconducting wire; b) providing a source of Sn within the subelement; c) assembling the metals within the subelement, the relative sizes and ratios of Nb, Cu and Sn being selected such that (i) the Nb fraction of the subelement cross section including and within the diffusion barrier is from 50 to 65% by area; (ii) the atomic ratio of the Nb to Sn including and within the diffusion barrier of the subelement is from 2.7 to 3.7; (iii) the ratio of the Sn to Cu within the diffusion barrier of the subelement is such that the Sn wt %/(Sn wt %+Cu wt %) is 45%-65%; (iv) the Cu to Nb local area ratio (LAR) of the Cu-encased Nb rods is from 0.10 to 0.30; (v) the Nb diffusion barrier being fully or partially converted to Nb.sub.3Sn by subsequent heat treatment; and (vi) the thickness of the Nb diffusion barrier is greater than the radius of the Nb portions of the Cu encased Nb rods; and d) assembling the subelements in a further matrix and reducing the assemblage to wire form such that (i) the multifilamentary Nb.sub.3Sn superconducting wire is formed of a plurality of the subelements, each having a Nb diffusion barrier to thereby form a wire having a distributed barrier design; (ii) the Nb portions of the copper encased Nb rods in the final wire are of diameter from 0.5 to 7 μm before reaction, and (iii) the Nb diffusion barrier that is fully or partially converted to Nb.sub.3Sn by heat treatment is from 0.8 to 11 μm thickness before reaction; and e) heat treating the final size wire from step d) to form the Nb.sub.3Sn superconducting phases, and multifilament Nb.sub.3Sn superconducting wires made thereby are described herein.

Methods for producing a multifilament Nb.sub.3Sn superconducting wire having a Jc value of at least 2000 A/mm.sup.2 at 4.2 K and 12 T by a) packing a plurality of Cu encased Nb rods within a first matrix which is surrounded by an intervening Nb diffusion barrier and a second matrix on the other side of the barrier remote from the rods thereby forming a packed subelement for the superconducting wire; b) providing a source of Sn within the subelement; c) assembling the metals within the subelement, the relative sizes and ratios of Nb, Cu and Sn being selected such that (i) the Nb fraction of the subelement cross section including and within the diffusion barrier is from 50 to 65% by area; (ii) the atomic ratio of the Nb to Sn including and within the diffusion barrier of the subelement is from 2.7 to 3.7; (iii) the ratio of the Sn to Cu within the diffusion barrier of the subelement is such that the Sn wt %/(Sn wt %+Cu wt %) is 45%-65%; (iv) the Cu to Nb local area ratio (LAR) of the Cu-encased Nb rods is from 0.10 to 0.30; (v) the Nb diffusion barrier being fully or partially converted to Nb.sub.3Sn by subsequent heat treatment; and (vi) the thickness of the Nb diffusion barrier is greater than the radius of the Nb portions of the Cu encased Nb rods; and d) assembling the subelements in a further matrix and reducing the assemblage to wire form such that (i) the multifilamentary Nb.sub.3Sn superconducting wire is formed of a plurality of the subelements, each having a Nb diffusion barrier to thereby form a wire having a distributed barrier design; (ii) the Nb portions of the copper encased Nb rods in the final wire are of diameter from 0.5 to 7 μm before reaction, and (iii) the Nb diffusion barrier that is fully or partially converted to Nb.sub.3Sn by heat treatment is from 0.8 to 11 μm thickness before reaction; and e) heat treating the final size wire from step d) to form the Nb.sub.3Sn superconducting phases, and multifilament Nb.sub.3Sn superconducting wires made thereby are described herein.

A composite crucible for growing single crystals comprises an outer crucible of a first material, and an inner liner of a second material having a coefficient of thermal expansion differing from the first material. The outer crucible comprises an inside bore. The inner liner is disposed in the inside bore without diffusion bonding or chemical bonding between the outer crucible and the inner liner. In certain non-limiting embodiments, the first material is one of molybdenum and a molybdenum alloy, and the second material is one of tantalum, niobium, a tantalum alloy, and a niobium alloy.

A composite crucible for growing single crystals comprises an outer crucible of a first material, and an inner liner of a second material having a coefficient of thermal expansion differing from the first material. The outer crucible comprises an inside bore. The inner liner is disposed in the inside bore without diffusion bonding or chemical bonding between the outer crucible and the inner liner. In certain non-limiting embodiments, the first material is one of molybdenum and a molybdenum alloy, and the second material is one of tantalum, niobium, a tantalum alloy, and a niobium alloy.

Disclosed is a method for preparing vanadium or vanadium alloy powder from a vanadium-containing raw material through a shortened process, including: calcinating a mixture of a vanadium-containing raw material and an alkali compound for oxidation to form a water-soluble vanadate; purifying the vanadate followed by vanadium precipitation to produce an intermediate CaV.sub.2O.sub.6 with high purity; dissolving CaV.sub.2O.sub.6 in a molten-salt medium together with other raw materials to form a uniform reaction system; and introducing a reducing agent to the system followed by separation, washing and drying to produce vanadium or vanadium alloy powder having a particle size of 50-800 nm and a purity of 99.0 wt % or more. The method can continuously process vanadium-containing raw materials to prepare vanadium or vanadium alloy powder.

A method for preparing a tantalum power of capacitor grade, comprising: solid tantalum nitride is added when potassium fluotantalate is reduced by sodium. The method increases the nitrogen content in the tantalum powder, and at the same time improves the electrical performance of the tantalum powder. The specific capacitance is increased, and the leakage current and loss is improved. The qualification rate of the anode and the capacitor product is also improved. The method is characterized in that the nitrogen in the tantalum nitride diffuses between the particles of the tantalum powder, with substantially no loss, and thus the nitrogen content is accurate and controllable.