Method for producing alloy ingots

Abstract

The invention relates to a method of producing metallic and intermetallic alloy ingots by continuous or quasi-continuous billet withdrawal from a cold wall crucible, which is characterized in that the alloy material is continuously or quasi-continuously supplied in a molten and pre-homogenized state to a cold wall induction crucible.

1 . A method of producing metallic and intermetallic alloy ingots by continuous or quasi-continuous billet withdrawal from a cold wall induction crucible, wherein the alloy material is supplied in a molten and pre-homogenized state continuously or quasi-continuously to a cold wall induction crucible.  
   
   
       2 . A method according to  claim 1 , wherein inter-metallic γ-TiAl-based alloy ingots are produced.  
   
   
       3 . A method according to  claim 1 , wherein the alloys are described by the following summation formula:  
       Ti x Al y (Cr,Mn,V) u (Zr,Cu,Nb,Ta,Mo,W,Ni) v (Si,B,C,Y) w    with the concentrations of the alloying constituents being within the following ranges (in atomic percent):    x=100-y-u-v-w    y=40 to 48, preferably 44 to 48    u=0.5 to 5    v=0.1 to 10 and    w=0.05 to 1.    
   
   
       4 . A method of producing metallic and intermetallic alloy ingots of high homogeneity and low porosity of any adjustable diameter according to  claim 1 , comprising the following method steps: 
 (i) producing electrodes by customarily mixing and compressing the selected starting materials;    (ii) at least once remelting the electrodes obtained in step (i) in a conventional fusion-metallurgical process;    (iii) inductively melting off the electrodes obtained in steps (i) and (ii) in a high frequency coil;    (iv) homogenizing the pre-homogenized, molten material obtained in step (iii) in a cold wall induction crucible; and    (v) withdrawing the melt, solidified by cooling, from the cold wall induction crucible of step (iv) in the form of solidified ingots of freely adjustable diameters and lengths.    
   
   
       5 . A method according to  claim 1 , comprising the following method steps: 
 (i) producing electrodes by conventionally mixing and compressing the selected starting materials;    (ii) at least once melting the electrodes obtained in step (i) by a conventional fusion-metallurgical method;    (iii) producing a pre-homogenized, molten material of the electrode material obtained in step (ii) by melting off in a cold crucible plasma furnace;    (iv) homogenizing the pre-homogenized, molten material obtained in step (iii) in a cold wall induction crucible; and    (v) withdrawing the melt, solidified by cooling, from the cold wall induction crucible of step (iv) in the form of cylindrical ingots of freely adjustable diameters and lengths.    
   
   
       6 . A method according to  claim 1 , wherein the melting process for producing the pre-homogenized, molten material takes place in a high frequency field of a frequency in the range of 70 to 300 kHz.  
   
   
       7 . A method according to  claim 1 , wherein the temperature of the pre-homogenized, molten material ranges between 1400 to 1600° C.  
   
   
       8 . A method according to  claim 4 , wherein the electrodes (iii) used for producing the molten, pre-homogenized material by means of an induction coil rotate preferably at a speed between 2 and 5 rpm.  
   
   
       9 . A method according to  claim 1 , wherein the method is executed quasi-continuously by one or several electrodes, in case of inductive melting, being quasi-continuously fed while an ingot is simultaneously withdrawn from the cold wall induction crucible.  
   
   
       10 . A method according to  claim 4 , wherein homogenization in the cold wall induction crucible in step (iv) takes place at a temperature of 1400 to 1700° C.  
   
   
       11 . A method according to  claim 4 , wherein homogenization in the cold wall induction crucible in step (iv) takes place in a range of frequency of 4 to 20 kHz.  
   
   
       12 . A method according to  claim 4 , wherein cooling the melt upon ingot withdrawal in step (v) takes place by the aid of water-cooled copper segments.  
   
   
       13 . A method according to  claim 4 , wherein the diameter of the ingots withdrawn in step (v) is in the range of 40 to 350 mm.  
   
   
       14 . γ-TiAl-based alloy ingots produced according to  claim 1 , comprising 
 (a) a length to diameter ratio of>12;    (b) homogeneity related to local macroscopic fluctuations of the aluminum and titanium of maximally ±0.5 atomic percent; further metallic alloying constituents of maximally ±0.2 atomic percent; non-metallic alloying additions (boron, carbon, silicon) of maximally ±0.05 atomic percent.    
   
   
       15 . A method according to  claim 5 , wherein the electrodes (iii) used for producing the molten, pre-homogenized material by means of an induction coil rotate preferably at a speed between 2 and 5 rpm.  
   
   
       16 . A method according to  claim 5 , wherein homogenization in the cold wall induction crucible in step (iv) takes place at a temperature of 1400 to 1700° C.  
   
   
       17 . A method according to  claim 5 , wherein homogenization in the cold wall induction crucible in step (iv) takes place in a range of frequency of 4 to 20 kHz.  
   
   
       18 . A method according to  claim 5 , wherein cooling the melt upon ingot withdrawal in step (v) takes place by the aid of water-cooled copper segments.  
   
   
       19 . A method according to  claim 5 , wherein the diameter of the ingots withdrawn in step (v) is in the range of 40 to 350 mm.