Microstructure of nbc-based cemented carbide

Abstract

Provided are niobium carbide-based cemented carbides and methods of manufacturing the same. The niobium carbide-based cemented carbides may be free of WC. Additionally, or alternatively, the niobium carbide-based cemented carbides may have a hard phase in which NbC in present in an amount greater than any other element of the hard phase. The niobium carbide-based cemented carbide may also have a binder phase devoid of Co.

1 . A NbC-based cemented carbide, comprising:
 a binder phase comprising Ni;   a hard phase comprising NbC in an amount greater than any other element of the hard phase;   the hard phase comprising a core-rim structure, the core rim structure comprising NbC and mixed carbides of two or more of Nb, Mo and Ta.   
     
     
         2 . The cemented carbide according to  claim 1 , further comprising W and the rim of the core-rim structure comprises mixed carbides of two or more of any of Nb, Mo, Ta and W. 
     
     
         3 . The cemented carbide according to  claim 2 , wherein the core of the core-rim structure comprises (Nb,W)C. 
     
     
         4 . The cemented carbide according to  claim 1 , wherein the amount of Nb in the cemented carbide is greater than 65 wt %. 
     
     
         5 . The cemented carbide according to  claim 2 , wherein the amount of W in the cemented carbide is present in an amount of 1-15 wt. 
     
     
         6 . The cemented carbide according to  claim 1 , wherein the binder phase comprises Ni in an amount greater than any other element of in the binder phase. 
     
     
         7 . The cemented carbide according to  claim 1 , wherein the Ni is present in an amount of at least 3 wt %. 
     
     
         8 . The cemented carbide according to  claim 1 , wherein the TaC is present in an amount of is at least 0.3 wt %. 
     
     
         9 . The cemented carbide according to  claim 1 , in an amount of less than 1 wt %. 
     
     
         10 . The cemented carbide according to  claim 1 , wherein the binder phase consists of Ni or Ni and Co; the hard phase consists of NbC or NbC and W; the core-rim structure comprises a core and a rim, the core consisting of NbC or NbC and (Nb,W)C and the rim consisting of mixed carbides of at least Nb, Mo and Ta, and optionally W. 
     
     
         11 . The cemented carbide according to  claim 1 , wherein the binder phase comprises 3-15 wt % Ni and optionally Co; the NbC is present in the hard phase in an amount greater than 65 wt %; the core-rim structure comprises a core and a rim, the core comprising NbC and optionally (Nb,W)C, and the rim of said core-rim structure comprising carbides and/or mixed carbides or any of at least Nb, Mo, Ta and optionally W. 
     
     
         12 . The cemented carbide according to  claim 1 , further including a crack having an intergranular path. 
     
     
         13 . A method of making a cemented carbide article comprising a binder phase and a hard phase, the hard phase comprising a core-rim structure, the method comprising:
 preparing a batch of powdered materials comprising Ni, NbC, Mo 2 C and TaC;   pressing the batch of powdered materials to form a pre-form; and sintering the pre-form to form the article.   
     
     
         14 . The method according to  claim 13 , wherein the powdered batch of powdered materials further comprises WC in an amount 0-15 wt %. 
     
     
         15 . The method according to  claim 13 , wherein the powdered batch comprises, in wt %,
 65-85 NbC;   3-15 Ni;   2-10 Mo 2 C;   1-8 TaC; and   0-6 WC.   
     
     
         16 . (canceled)