Method for producing magnetostrictive element

Abstract

It is an object of the present invention to provide a method for producing a magnetostrictive element which can give an anisotropic magnetostrictive element from a starting material containing Sm and a transition metal element. The method produces an anisotropic magnetostrictive element by compacting the starting powder in a magnetic field to produce a compact, and sintering the compact to produce a sintered body having a composition of SmFe 2 . It is preferable that the starting powder is produced by mixing a first alloy for the main phase of the magnetostrictive element with a second alloy having a lower melting point than the first alloy. It is recommended that the first alloy has a larger particle size than the second alloy.

1 . A method for producing an anisotropic magnetostrictive element, comprising the steps of: 
 compacting a starting powder containing at least Sm and Fe into a compact in a magnetic field, and    sintering the compact to produce a sintered body having a composition of SmFe 2 .    
   
   
       2 . The method for producing a magnetostrictive element according to  claim 1 , wherein the starting powder is produced by mixing a first alloy which forms the main phase of the magnetostrictive element with a second alloy which has a lower melting point than the first alloy.  
   
   
       3 . The method for producing a magnetostrictive element according to  claim 2 , wherein the first alloy has a composition of SmFe 1.96 .  
   
   
       4 . The method for producing a magnetostrictive element according to  claim 2  or  3 , wherein the second alloy has a composition of Sm 2.0 Fe.  
   
   
       5 . The method for producing a magnetostrictive element according to  claim 2 , wherein the starting powder contains the first alloy at 70% by weight or more but below 100% by weight.  
   
   
       6 . The method for producing a magnetostrictive element according to  claim 2 , wherein the starting powder contains the first alloy between 80 and 95% by weight.  
   
   
       7 . The method for producing a magnetostrictive element according to  claim 2 , wherein the first alloy powder has a larger particle size than the second alloy powder.  
   
   
       8 . The method for producing a magnetostrictive element according to  claim 7 , wherein the first alloy powder has a mean particle size of 12 to 30 μm.  
   
   
       9 . The method for producing a magnetostrictive element according to  claim 7 , wherein the first alloy powder is mainly composed of single crystalline particles and heat-treated beforehand to have a larger particle size than the second alloy powder.  
   
   
       10 . The method for producing a magnetostrictive element according to  claim 9 , wherein the first alloy powder is heat-treated at 850 to 900° C. for 6 to 48 hours, in a non-oxidative atmosphere.  
   
   
       11 . The method for producing a magnetostrictive element according to  claim 1 , wherein the compact is sintered at 800 to 900° C. for 3 to 48 hours, in a non-oxidative atmosphere.  
   
   
       12 . The method for producing a magnetostrictive element according to any of  claim 1 , wherein the starting powder is oriented in a magnetic field of 450 to 1760 kA/m in the step of producing a compact.  
   
   
       13 . A method for producing an anisotropic magnetostrictive element, comprising the steps of: 
 mixing a first alloy powder which has a composition of SmFe 1.69  with a second alloy powder which has a composition of Sm 2.0 Fe to prepare a starting powder,    compacting the starting powder into a compact in a magnetic field, and    sintering the compact to produce a sintered body having a composition of SmFe 2 .    
   
   
       14 . The method for producing a magnetostrictive element according to  claim 13 , wherein the starting powder contains the first alloy between 80 and 95% by weight.  
   
   
       15 . The method for producing a magnetostrictive element according to  claim 13 , wherein the first alloy powder has a mean particle size of 12 to 30 μm, and the second alloy powder has a smaller particle size than the first alloy powder.  
   
   
       16 . The method for producing a magnetostrictive element according to  claim 15 , wherein the first alloy powder is mainly composed of single crystalline particles.  
   
   
       17 . The method for producing a magnetostrictive element according to  claim 13 , wherein the sintered body is polycrystalline and the grains of the sintered body are oriented along the [111] axis.