Abstract:
A tungsten wire containing 1−10 mass% of rhenium, characterized in that the point showing 2% expansion of a heated tungsten wire having a diameter of x µm and heated by application of a current of which the ratio to the fusing current (FC) of the tungsten wire of x µm diameter is y% is within the quadrilateral defined by connecting point (20, 75), point (20, 87), point (90, 75), and point (90, 58) by straight lines in a semilogarithmic coordinate system in which point (x, y) is shown, of which the horizontal axis is marked with a logarithmic scale of diameter x, and of which the vertical axis is marked with an ordinary scale of the ratio y to the fusing current. The tungsten wire expands greatly even under high−temperature condition, exhibits excellent durability when used as a constituent material of, e.g., a cathode heater and can be produced efficiently.