Hydrogen storage alloy and producing method thereof

Abstract

To produce a hydrogen storage alloy by melting a hydrogen storage alloy having a body-centered cubic crystal structure without using a refractory crucible and solidifying a molten alloy by a unidirectional solidification process. The unidirectional solidification is carried out by a cold crucible induction melting method at a moving speed of a solid-liquid interface in the range of 10 to 200 mm/hr by using a water-cooled metal crucible in a vacuum or an inert gas atmosphere.

1 . A method of producing a hydrogen storage alloy, comprising: 
 melting a hydrogen storage alloy having a body-centered cubic crystal structure without using a refractory crucible; and    solidifying a molten alloy by a unidirectional solidification process.    
   
   
       2 . The method of producing a hydrogen storage alloy according to  claim 1 , 
 wherein the hydrogen storage alloy is melted in a water-cooled metal crucible.    
   
   
       3 . The method of producing a hydrogen storage alloy according to  claim 1 , 
 wherein the metal crucible comprises copper.    
   
   
       4 . The method of producing a hydrogen storage alloy according to  claim 1 , 
 wherein a speed of the unidirectional solidification process is set at a moving speed of a solid-liquid interface in a range of 10 to 200 mm/hr.    
   
   
       5 . The method of producing a hydrogen storage alloy according to  claim 4 , 
 wherein the speed of the unidirectional solidification process is set at the moving speed of a solid-liquid interface in a range of 12 to 60 mm/hr.    
   
   
       6 . The method of producing a hydrogen storage alloy according to  claim 1 , 
 wherein the hydrogen storage alloy is melted and unidirectionally solidified in a vacuum or an inert gas atmosphere.    
   
   
       7 . The method of producing a hydrogen storage alloy according to  claim 1 , 
 wherein the unidirectional solidification is carried out by a cold crucible induction melting method.    
   
   
       8 . The method of producing a hydrogen storage alloy according to  claim 7 , 
 wherein the unidirectional solidification is carried out by disposing a water-cooled metallic crucible along an axial direction inside of an induction heating coil, and moving the metallic crucible relatively to the induction heating coil in a direction opposite to a solidification direction.    
   
   
       9 . A hydrogen storage alloy having a body-centered cubic structure that is produced by the method according to  claim 1.