Microalloying of niobium alloys

Abstract

The present disclosure is directed to methods for preparing a refractory alloy or recycled alloy using a niobium base alloy. In one embodiment, a niobium base alloy is microalloyed with one or more reactive element to form an intermediate alloy. Carbon is then added to the intermediate alloy to form the refractory alloy or recycled alloy. The disclosure is also directed to the refractory alloy or recycled alloy prepared according to the described methods.

1 . A method of preparing a refractory alloy, the method comprising:
 microalloying a niobium base alloy with one or more reactive element selected from the group consisting of Sc, Y, Er, Gd, Ce or combinations thereof, to form an intermediate alloy; and   adding carbon to the intermediate alloy to form the refractory alloy;   wherein the niobium base alloy optionally further comprises Hf, Ti, Mo, V, Zr, W, Ta, or combinations thereof.   
     
     
         2 . The method of  claim 1 , wherein the niobium base alloy comprises:
 from about 0 wt % to about 25 wt % Hf;   from about 0.5 wt % to about 2.5 wt % Ti;   from about 0 wt % to about 5 wt % Mo;   from about 0 wt % to about 5 wt % V;   from about 0 wt % to about 1 wt % Zr;   from about 0 wt % to about 15 wt % W; and   the remainder Nb together with unavoidable impurities.   
     
     
         3 . The method of  claim 2 , wherein the unavoidable impurities comprise one or more of Al, Cr, Si, B, and Fe. 
     
     
         4 . The method of  claim 1 , wherein the niobium base alloy is selected from the group consisting of C-103, Nb-1Zr, PWC-11, Cb752, and Cb129Y. 
     
     
         5 . The method of  claim 4 , wherein the niobium base alloy is C-103. 
     
     
         6 . The method of  claim 1 , wherein microalloying further comprises the addition of Al, Cr, Si, B, Fe, W, or combinations thereof. 
     
     
         7 . The method of  claim 6 , wherein refractory alloy comprises:
 about 0.1 wt % or less, about 0.075 wt % or less, about 0.05 wt % or less, about 0.0025 wt % or less, or about 0.01 wt % or less of Al;   about 0.1 wt % or less, about 0.075 wt % or less, about 0.05 wt % or less, about 0.0025 wt % or less, or about 0.01 wt % or less of Cr;   about 0.1 wt % or less, about 0.075 wt % or less, about 0.05 wt % or less, about 0.0025 wt % or less, or about 0.01 wt % or less of Si;   about 0.1 wt % or less, about 0.075 wt % or less, about 0.05 wt % or less, about 0.0025 wt % or less, or about 0.01 wt % or less of B; and/or   about 0.1 wt % or less, about 0.075 wt % or less, about 0.05 wt % or less, about 0.0025 wt % or less, or about 0.01 wt % or less of Fe.   
     
     
         8 . The method of  claim 6 , wherein the total concentration of Al, Cr, Si, B, and Fe in the refractory alloy is less than about 0.5 wt %, less than about 0.4 wt %, less than about 0.3 wt %, less than about 0.2 wt %, or less than about 0.1 wt %. 
     
     
         9 . The method of  claim 1 , wherein the refractory alloy comprises from about 0 wt % to about 0.15 wt %, from about 0.01 wt % to about 0.14 wt %, from about 0.01 wt % to about 0.13 wt %, from about 0.01 wt % to about 0.12 wt %, from about 0.01 wt % to about 0.11 wt %, from about 0.01 wt % to about 0.1 wt %, from about 0.02 wt % to about 0.1 wt %, from about 0.02 wt % to about 0.09 wt %, from about 0.02 wt % to about 0.08 wt %, from about 0.03 wt % to about 0.08 wt %, from about 0.03 wt % to about 0.07 wt %, from about 0.03 wt % to about 0.06 wt %, or from about 0.04 wt % to about 0.06 wt % of the one or more reactive element. 
     
     
         10 . The method of  claim 1 , wherein when the one or more reactive element comprises Ce, the refractory alloy comprises from about 0.01 wt % to about 0.1 wt %, from about 0.01 wt % to about 0.09 wt %, from about 0.01 wt % to about 0.08 wt %, from about 0.02 wt % to about 0.08 wt %, from about 0.02 wt % to about 0.07 wt %, from about 0.02 wt % to about 0.06 wt %, or from about 0.03 wt % to about 0.05 wt % of Ce. 
     
     
         11 . The method of  claim 1 , wherein the total concentration of the one or more reactive element in the refractory alloy is less than about 0.5 wt %, less than about 0.4 wt %, less than about 0.3 wt %, less than about 0.2 wt %, or less than about 0.1 wt %. 
     
     
         12 . The method of  claim 1 , wherein the total concentration of the one or more reactive element in the refractory alloy is from about 0.01 wt % to about 0.5 wt %, from about 0.02 wt % to about 0.5 wt %, from about 0.03 wt % to about 0.5 wt %, from about 0.04 wt % to about 0.5 wt %, from about 0.05 wt % to about 0.5 wt %, from about 0.05 wt % to about 0.4 wt %, from about 0.05 wt % to about 0.3 wt %, from about 0.06 wt % to about 0.3 wt %, from about 0.07 wt % to about 0.3 wt %, from about 0.07 wt % to about 0.25 wt %, from about 0.08 wt % to about 0.25 wt %, from about 0.09 wt % to about 0.25 wt %, from about 0.1 wt % to about 0.25 wt %, from about 0.12 wt % to about 0.25 wt %, from about 0.14 wt % to about 0.25 wt %, from about 0.16 wt % to about 0.25 wt %, from about 0.18 wt % to about 0.25 wt %, or from about 0.2 wt % to about 0.25 wt %. 
     
     
         13 . The method of  claim 1 , wherein the one or more reactive element is selected from the group consisting of Sc, Y, Er, Gd and combinations thereof. 
     
     
         14 . The method of  claim 1 , wherein the interstitial oxygen content of the intermediate alloy is less than the interstitial oxygen content of the niobium base alloy. 
     
     
         15 . The method of  claim 1 , wherein the intermediate alloy has an interstitial oxygen content of about 0.1 wt % or less, about 0.09 wt % or less, about 0.08 wt % or less, about 0.07 wt % or less, about 0.06 wt % or less, about 0.05 wt % or less, about 0.04 wt % or less, about 0.03 wt % or less, about 0.02 wt % or less, about 0.01 wt % or less, or about 0.005 wt % or less. 
     
     
         16 . The method of  claim 1 , wherein the interstitial oxygen content of the refractory alloy is less than the interstitial oxygen content of the niobium base alloy. 
     
     
         17 . The method of  claim 1 , wherein the refractory alloy has an interstitial oxygen content of about 0.1 wt % or less, about 0.09 wt % or less, about 0.08 wt % or less, about 0.07 wt % or less, about 0.06 wt % or less, about 0.05 wt % or less, about 0.04 wt % or less, about 0.03 wt % or less, about 0.02 wt % or less, about 0.01 wt % or less, or about 0.005 wt % or less. 
     
     
         18 . The method of  claim 1 , wherein the total concentration of carbon, oxygen, and nitrogen in the refractory alloy is less than about 0.5 wt %, less than about 0.4 wt %, less than about 0.3 wt %, less than about 0.2 wt %, less than about 0.1 wt %, or less than about 0.05 wt %. 
     
     
         19 . A refractory alloy of the formula:
 Nb-10Hf-1Ti-0.15C-0.05Y-0.1Gd;   Nb-10Hf-1.5Ti-0.10C-0.10Er-0.15Al-0.05Si;   Nb-10Hf-5Mo-5V-1Zr-0.08C-0.08Sc;   Nb-5Hf-10W-1Zr-0.10C-0.08Y-0.05Er; or   Nb-12Hf-1Ti-1Zr-0.10C-0.08Er-0.15Al-0.08Y-0.1Si;   wherein the refractory alloy is formed by a process comprising:   microalloying a niobium base alloy with one or more reactive element selected from the group consisting of Sc, Y, Er, Gd, Ce or combinations thereof, to form an intermediate alloy; and   adding carbon to the intermediate alloy to form the refractory alloy.   
     
     
         20 . A refractory alloy of the formula:
 Nb-10Hf-1Ti-0.15C-0.05Y-0.1Gd;   Nb-10Hf-1.5Ti-0.10C-0.10Er-0.15Al-0.05Si;   Nb-10Hf-5Mo-5V-1Zr-0.08C-0.08Sc;   Nb-5Hf-10W-1Zr-0.10C-0.08Y-0.05Er; or   Nb-12Hf-1Ti-1Zr-0.10C-0.08Er-0.15Al-0.08Y-0.1Si.