Method for purification of metal based alloy and intermetallic powders

Abstract

This invention relates to a method for purifying metal alloy and intermetallic powders. Particularly, the present invention relates to a method for the reduction or elimination of the content of the dissolved oxygen and to remove the metal oxide inclusions from metal alloy and intermetallic powders including the steps of: a) placing the metal in powder form into a reaction apparatus; b) introducing a suitable carrier substance to the metal powder; and c) introducing calcium vapour into the reaction apparatus to create a reaction between the metallic powder and calcium vapour thereby removing inclusions in the metal as shown in FIG. 11.

1 . A method of purifying a metal comprising:
 (a) placing the metal in powder form into a reaction apparatus;   (b) introducing to the metal powder a suitable carrier substance which can suspend the powder particles; and   (c) introducing a deoxidant calcium vapor into the reaction apparatus to create a reaction between the metallic powder and calcium vapor thereby removing inclusions in the metal.   
   
   
       2 . A method as claimed in  claim 1 , wherein said calcium vapor is introduced through introducing calcium hydride vapor. 
   
   
       3 . A method as claimed in  claim 1 , wherein particles of the metal in powder form are less than 100 micrometres. 
   
   
       4 . A method as claimed in  claim 1 , wherein the inclusions are oxygen containing compounds. 
   
   
       5 . A method as claimed in  claim 4 , wherein the inclusions are Al 2 O 3 . 
   
   
       6 . A method as claimed in  claim 1 , wherein the metal is a Ti x Al compound. 
   
   
       7 . A method as claimed in  claim 1 , wherein the metal powder is homogeneously mixed with the carrier substance. 
   
   
       8 . A method as claimed in  claim 7 , wherein the carrier substance is calcium chloride (CaCl 2 ). 
   
   
       9 . A method as claimed in  claim 7 , wherein the carrier substance is hydrated calcium chloride (CaCl 2 .H 2 O). 
   
   
       10 . A method as claimed in  claim 1 , wherein calcium is a metal deoxidant in the form of a solid. 
   
   
       11 . A method as claimed in  claim 10 , wherein the calcium solid is granules. 
   
   
       12 . A method as claimed in  claim 11 , wherein the calcium granules are kept in separate chambers of the apparatus and heated to a temperature in the range of 700-1400° C. 
   
   
       13 . A method as claimed in  claim 12 , wherein the calcium granules are heated at 700-1400° C. for a time period of 1 minute to 100 hours to allow generation of calcium vapor. 
   
   
       14 . A method as claimed in  claim 12 , wherein the calcium vapor generated during heating is introduced to another apparatus chamber where the mixture of the metal and the carrier substance is kept and heated to the same temperature range of 700-1400° C. 
   
   
       15 . A method of purifying a metal as claimed in  claim 1 , wherein the temperature allows the carrier substance to melt and a substantive fraction of the metal deoxidant to turn into vapor. 
   
   
       16 . A method of purifying a metal as claimed in  claim 6 , wherein interactions between calcium atoms and the Ti x Al powder particles are dispersed in the liquid carrier substance through a liquid medium. 
   
   
       17 . (canceled) 
   
   
       18 . A method as claimed in  claim 2 , wherein the inclusions are oxygen containing compounds. 
   
   
       19 . A method as claimed in  claim 3 , wherein the inclusions are oxygen containing compounds. 
   
   
       20 . A method as claimed in  claim 2 , wherein the metal is a Ti x Al compound. 
   
   
       21 . A method as claimed in  claim 3 , wherein the metal is a Ti x Al compound.