Method for manufacturing alloy containing transition metal carbide, tungsten alloy containing transition metal carbide, and alloy manufactured by said method

Abstract

The present invention relates to the development of an alloy material with significantly improved low-temperature brittleness, recrystallization brittleness, and irradiation brittleness by the introduction of a recrystallization microstructure into an alloy, particularly a tungsten material, to significantly strengthen a weak grain boundary of the recrystallization microstructure. The present invention comprises the steps of: mechanically alloying at least one species selected from a group-IVA, VA, or VIA transition metal carbide and a metallic raw material; sintering base powders obtained through the mechanically alloying step, by using a hot isostatic press; and performing plastic deformation of at least 60% on the alloy obtained through the sintering step, at a strain rate between 10 −5 s −1 and 10 −2 S −1 and at a temperature between 500° C. and 2,000° C. It is therefore possible to obtain an alloy material with significantly improved low-temperature brittleness, recrystallization brittleness, and irradiation brittleness.

1 . A method for manufacturing an alloy, characterized by having a step for mechanical alloying of a metal raw material and at least one selected from carbides of group IVA, VA, or VIA transition metals, a step for sintering the raw material powder obtained in said mechanical alloying step using hot isostatic pressing, and a step for subjecting the alloy obtained in said sintering step to grain boundary sliding based plastic deformation of 60% or greater at 500 to 2000° C. and a strain rate of 10 −5  s −1  to 10 −2  s −1 . 
     
     
         2 . The method for manufacturing an alloy according to  claim 1 , characterized by having a step in which said transition metal carbide and the metal raw material are degassed by heating prior to said mechanical alloying step. 
     
     
         3 . A tungsten alloy comprising 0.25 to 5 mass % of at least one type selected from carbides of a group IVA, VA, or VIA transition metals, the tungsten alloy characterized in that the oxygen content is 950 ppm by mass or less, the nitrogen content is 60 ppm by mass or less, 80% or more of an observed cross sectional area in the tungsten phase is recrystallized equiaxed grains with grain diameters of 0.05 to 10 μm, the ductile-brittle transition temperature determined by three-point flexure is 500K or less, and plastic deformation due to grain boundary sliding is possible at or above this temperature. 
     
     
         4 . The tungsten alloy according to  claim 3 , characterized in that 90% or greater of the azimuths of the carbide present in the tungsten alloy structure and the azimuths of the tungsten matrix are in the (Kurdjumov-Sachs) azimuth relationship: {111} W//{110} transition metal carbide <110> W//<111> transition metal carbide. 
     
     
         5 . The tungsten alloy according to  claim 3 , characterized in that the full width at half maximum for reflection of the (220) diffraction planes is 3° or less as determined by X-ray diffraction, or that there are 50 or fewer dislocations within crystal grains as determined by transmission electron microscopy. 
     
     
         6 . The tungsten alloy according to  claim 3 , characterized in that the maximum bend strength determined by three-point flexure is 1470 MPa or greater. 
     
     
         7 . The alloy that is manufactured by the manufacturing method according to  claim 1 . 
     
     
         8 . The tungsten alloy according to  claim 4 , characterized in that the full width at half maximum for reflection of the (220) diffraction planes is 3° or less as determined by X-ray diffraction, or that there are 50 or fewer dislocations within crystal grains as determined by transmission electron microscopy. 
     
     
         9 . The tungsten alloy according to  claim 4 , characterized in that the maximum bend strength determined by three-point flexure is 1470 MPa or greater. 
     
     
         10 . The tungsten alloy according to  claim 5 , characterized in that the maximum bend strength determined by three-point flexure is 1470 MPa or greater. 
     
     
         11 . The alloy that is manufactured by the manufacturing method according to  claim 2 .