High temperature shape memory alloy, actuator and motor

Abstract

A high temperature shape memory alloy is provided which possesses high machinability and is suitable for high temperature applications. The high temperature shape memory alloy consists of Ni from 34.7 mol % to 48.5 mol %, at least either Zirconium or Hafnium as transformation temperature increasing additives, with the sum of which 6.8 mol % to 22.5 mol %, and at least either Niobium or Tantalum as machinability improving additives, with the sum of which 1 mol % to 30 mol %; and Boron less than 2 mol %; and Titanium as the balance; and unavoidable impurity.

1 . A high temperature shape memory alloy, wherein said alloy consists of 34.7 mol %-48.5 mol % Ni, at least either Zirconium or Hafnium as transformation temperature increasing additive elements, with the sum of which 6.8 mol % to 22.5 mol %; at least either Niobium or Tantalum as machinability improving additives, with the sum of which 1 mol % to 30 mol %; and Boron less than 2 mol %; and Titanium and impurities as the balance. 
     
     
         2 . A high temperature shape memory alloy according to  claim 1 , wherein said alloy consists of 6.8 mol % to 22.5 mol % Zirconium as said transformation temperature increasing additives; and 3 mol % to 30 mol % Niobium as said machinability improving additives. 
     
     
         3 . A high temperature shape memory alloy according to  claim 1 , wherein said alloy consists of 6.8 mol % to 18 mol % Hafnium as said transformation temperature increasing additives; and 3 mol % to 20 mol % Niobium as said machinability improving additives. 
     
     
         4 . A high temperature shape memory alloy according to  claim 1 , wherein said alloy consists of 6.8 mol % to 20 mol % said transformation temperature increasing additives; and 3 mol % to 30 mol % Tantalum as said machinability improving additives. 
     
     
         5 . A high temperature shape memory alloy according to  claim 1 , wherein the mol ratio of Titanium plus Zirconium and Hafnium to Nickel is in the range of 0.98 to 1.14. 
     
     
         6 . An actuator, wherein the said actuator is made of the high temperature shape memory alloy described in  claim 1 . 
     
     
         7 . A motor equipped with a flux adjusting valve, wherein the said flux adjusting valve is made of the high temperature shape memory alloy described in  claim 1 . 
     
     
         8 . A shape memory alloy, comprising:
 nickel (Ni);   at least one of zirconium (Zr) and hafnium (Hf) as transformation temperature increasing additive elements;   at least one of niobium (Nb) and tantalum (Ta) as machinability improving additives; and   boron (B) in a concentration ranging between 0 mol %-2 mol %;   wherein the mol ratio of Titanium plus Zirconium and Hafnium to Nickel is between 0.98 to 1.14.   
     
     
         9 . The alloy of  claim 8 , wherein nickel is present in a concentration ranging between 34.7 mol %-48.5 mol %. 
     
     
         10 . The alloy of  claim 8 , wherein the sum of the concentration of zirconium and hafnium ranges between 6.8 mol %-22.5 mol %. 
     
     
         11 . The alloy of  claim 8 , wherein the sum of the concentration of niobium and tantalum ranges between 1 mol %-30 mol %. 
     
     
         12 . The alloy of  claim 8 , wherein the concentration of zirconium ranges between 6.8 mol %-22.5 mol % and the concentration of niobium ranges between 3 mol %-30 mol %. 
     
     
         13 . The alloy of  claim 8 , wherein the concentration of hafnium ranges between 6.8 mol %-18 mol % and the concentration of niobium ranges between 3 mol %-20 mol %. 
     
     
         14 . The alloy of  claim 8 , wherein the sum of the concentration of zirconium and hafnium ranges between 6.8 mol %-20 mol % and the concentration of tantalum ranges between 3 mol %-30 mol %. 
     
     
         15 . The alloy of  claim 8 , wherein the peak reverse transformation temperature (A*) is greater than 100° C. 
     
     
         16 . A method of making a shape memory alloy part, comprising:
 providing a shape memory alloy composition comprising:
 nickel in a concentration ranging between 34.7 mol %-48.5 mol %; 
 at least one of zirconium and hafnium, wherein the total concentration zirconium plus hafnium ranges between 1 mol %-30 mol %; 
 at least one of niobium and tantalum, wherein the total concentration niobium plus tantalum ranges between 6.8 mol %-22.5 mol %; and 
 boron (B) in a concentration below 2 mol %; 
 wherein the concentration of the elements is selected such that the mol ratio of Titanium plus Zirconium and Hafnium to Nickel is between 0.98 to 1.14; and 
   forming the shape memory alloy composition into the part.   
     
     
         17 . The method of  claim 16 , wherein the concentration of zirconium ranges between 6.8 mol %-22.5 mol % and the concentration of niobium ranges between 3 mol %-30 mol %. 
     
     
         18 . The method of  claim 16 , wherein the concentration of hafnium ranges between 6.8 mol %-18 mol % and the concentration of niobium ranges between 3 mol %-20 mol %. 
     
     
         19 . The method of  claim 16 , wherein the sum of the concentration of zirconium and hafnium ranges between 6.8 mol %-20 mol % and the concentration of tantalum ranges between 3 mol %-30 mol %. 
     
     
         20 . The method of  claim 16 , wherein the part comprises at least one of an actuator and a flux adjusting value configured for use with a motor.