Iron-based alloy and process for producing the same

Abstract

It is an object of the present invention to provide a ferromagnetic Fe-based alloy having a large reversible strain obtained by application and removal of a magnetic field gradient. The Fe-based alloy contains one or two or more types selected from Al: 0.01 to 11%, Si: 0.01 to 7% and Cr: 0.01 to 26%, or Al: 0.01 to 11%, Si: 0.01 to 7%, Cr: 0.01 to 26% and Ni: 35 to 50%. A twin crystal interface is introduced by working the Fe-based alloy at a working rate: 10% or more. An area ratio of the twin crystal interface to a crystal grain boundary is 0.2 or more. One or two or more types of Ti: 0.01 to 5%, V: 0.01 to 10%, Mn: 0.01 to 5%, Co: 0.01 to 30%, Ni: 0.01 to 10%, Cu: 0.01 to 5%, Zr: 0.01 to 5%, Nb: 0.01 to 5%, Mo: 0.01 to 5%, Hf: 0.01 to 5%, Ta: 0.01 to 5%, W: 0.01 to 5%, B: 0.001 to 1%, C: 0.001 to 1%, P: 0.001 to 1% and S: 0.001 to 1% may be added to the Fe-based alloy if needed.

1 . A magnetic drive actuator comprising Fe-based alloy displaced in accordance with application and removal of a magnetic field gradient, the Fe-based alloy comprising one or two or more types selected from Al: 0.01 to 11% by mass, Si: 0.01 to 7% by mass and Cr: 0.01 to 26% by mass, the balance including Fe and unavoidable impurities, an area ratio of a twin crystal interface to a crystal grain boundary being 0.2 or more. 
     
     
         2 . The magnetic drive actuator according to  claim 1 , the Fe-based alloy further comprising one or two or more types selected from Ti: 0.01 to 5% by mass, V: 0.01 to 10% by mass, Mn: 0.01 to 5% by mass, Co: 0.01 to 30% by mass, Ni: 0.01 to 10% by mass, Cu: 0.01 to 5% by mass, Zr: 0.01 to 5% by mass, Nb: 0.01 to 5% by mass, Mo: 0.01 to 5% by mass, Hf: 0.01 to 5% by mass, Ta: 0.01 to 5% by mass, W: 0.01 to 5% by mass, B: 0.001 to 1% by mass, C: 0.001 to 1% by mass, P: 0.001 to 1% by mass and S: 0.001 to 1% by mass. 
     
     
         3 . A magnetic drive actuator comprising Fe-based alloy displaced in accordance with application and removal of a magnetic field gradient, the Fe-based alloy comprising one or two or more types selected from Al: 0.01 to 11% by mass, Si: 0.01 to 7% by mass, Cr: 0.01 to 26% by mass and Ni: 35 to 50% by mass, the balance including Fe and unavoidable impurities, an area ratio of a twin crystal interface to a crystal grain boundary being 0.2 or more. 
     
     
         4 . The magnetic drive actuator according to  claim 3 , the Fe-based alloy further comprising one or two or more types selected from Ti: 0.01 to 5% by mass, V: 0.01 to 10% by mass, Mn: 0.01 to 5% by mass, Co: 0.01 to 30% by mass, Cu: 0.01 to 5% by mass, Zr: 0.01 to 5% by mass, Nb: 0.01 to 5% by mass, Mo: 0.01 to 5% by mass, Hf: 0.01 to 5% by mass, Ta: 0.01 to 5% by mass, W: 0.01 to 5% by mass, B: 0.001 to 1% by mass, C: 0.001 to 1% by mass, P: 0.001 to 1% by mass and S: 0.001 to 1% by mass. 
     
     
         5 . The magnetic drive actuator according to  claim 1 , wherein the area ratio of the twin crystal interface to the crystal grain boundary being 3.0 or less. 
     
     
         6 . The magnetic drive actuator according to  claim 5 , wherein the Fe-based alloy has a magnetization intensity of 100 emu/g or more in 0.5 tesla (T). 
     
     
         7 . A method for producing an Fe-based alloy for a magnetic drive actuator displacably controlled in accordance with application and removal of a magnetic field gradient, the method comprising:
 solution-treating the Fe-based alloy at a temperature range of 600 to 1350° C. for 0.1 to 6 hours, the Fe-based alloy comprising one or two or more types selected from Al: 0.01 to 11% by mass, Si: 0.01 to 7% by mass and Cr: 0.01 to 26% by mass, the balance including Fe and unavoidable impurities, an area ratio of a twin crystal interface to a crystal grain boundary being 0.2 or more; and   working the Fe-based alloy at a working rate: 10% or more.   
     
     
         8 . The method for producing the Fe-based alloy for a magnetic drive actuator according to  claim 7 , wherein the Fe-based alloy further comprises one or two or more types selected from Ti: 0.01 to 5% by mass, V: 0.01 to 10% by mass, Mn: 0.01 to 5% by mass, Co: 0.01 to 30% by mass, Ni: 0.01 to 10% by mass, Cu: 0.01 to 5% by mass, Zr: 0.01 to 5% by mass, Nb: 0.01 to 5% by mass, Mo: 0.01 to 5% by mass, Hf: 0.01 to 5% by mass, Ta: 0.01 to 5% by mass, W: 0.01 to 5% by mass, B: 0.001 to 1% by mass, C: 0.001 to 1% by mass, P: 0.001 to 1% by mass and S: 0.001 to 1% by mass. 
     
     
         9 . A method for producing an Fe-based alloy for a magnetic drive actuator displacably controlled in accordance with application and removal of a magnetic field gradient, the method comprising:
 solution-treating the Fe-based alloy at a temperature range of 600 to 1350° C. for 0.1 to 6 hours, the Fe-based alloy comprising one or two or more types selected from Al: 0.01 to 11% by mass, Si: 0.01 to 7% by mass, Cr: 0.01 to 26% by mass and Ni: 35 to 50% by mass, the balance including Fe and unavoidable impurities, an area ratio of a twin crystal interface to a crystal grain boundary being 0.2 or more; and   working the Fe-based alloy at a working rate: 10% or more.   
     
     
         10 . The method for producing the Fe-based alloy for a magnetic drive actuator according to  claim 9 , wherein the Fe-based alloy further comprises one or two or more types selected from Ti: 0.01 to 5% by mass, V: 0.01 to 10% by mass, Mn: 0.01 to 5% by mass, Co: 0.01 to 30% by mass, Cu: 0.01 to 5% by mass, Zr: 0.01 to 5% by mass, Nb: 0.01 to 5% by mass, Mo: 0.01 to 5% by mass, Hf: 0.01 to 5% by mass, Ta: 0.01 to 5% by mass, W: 0.01 to 5% by mass, B: 0.001 to 1% by mass, C: 0.001 to 1% by mass, P: 0.001 to 1% by mass and S: 0.001 to 1% by mass. 
     
     
         11 . The method for producing the Fe-based alloy for a magnetic drive actuator according to  claim 7 , wherein the Fe-based alloy is worked at 700° C. or less. 
     
     
         12 . The method for producing the Fe-based alloy for a magnetic drive actuator according to  claim 7 , wherein the Fe-based alloy is worked at a working rate of 95% or less. 
     
     
         13 . The method for producing the Fe-based alloy for a magnetic drive actuator according to  claim 7 , wherein the Fe-based alloy is aging-treated at a temperature range of 200 to 800° C. for 0.1 to 24 hours after the Fe-based alloy is worked. 
     
     
         14 . The method for producing the Fe-based alloy for a magnetic drive actuator according to  claim 7 , wherein the area ratio of the twin crystal interface to the crystal grain boundary is made to be 0.2 or more and 3.0 or less.