Low hysteresis materials and methods

Abstract

A method is provided for predicting material properties and creating or modifying materials to exhibit desired properties. Materials and devices are described that are formed using the methods. Using embodiments described above, a number of advantages are realized. One advantage includes an ability to predict hysteresis in a multiple phase material. One embodiment includes an ability to modify or create a material to exhibit low hysteresis. Using embodiments described above to predict material properties and modify material properties, a number of materials can be created. An improved shape memory alloy with low hysteresis can be created. Additionally, a material that exhibits any of a number of properties that are normally mutually exclusive can be created.

1 . A shape memory alloy, comprising: 
 a first phase component, wherein an amount of the first phase component is adapted for a substantially reversible transformation to a second phase component;    wherein a determinant of U 1  is between 0.995 and 1.005; and    wherein a second eigenvalue is between 0.9995 and 1.0005.    
   
   
       2 . The shape memory alloy of  claim 1 , wherein the shape memory alloy includes: 
 49.5-52.0 atomic % titanium    2.1-25.0 atomic % copper;    (10.8−0.011 Cu 2 )±0.2 atomic % palladium, where Cu is the atomic % copper; and    a balance of nickel.    
   
   
       3 . The shape memory alloy of  claim 1 , wherein the shape memory alloy includes: 
 25-35 atomic % nickel;    (50-Ni) atomic % palladium, where Ni is the atomic % nickel;    5-8 atomic % hafnium; and    a balance of titanium.    
   
   
       4 . A shape memory alloy, comprising: 
 25-35 atomic % nickel;    (50-Ni) atomic % platinum, where Ni is the atomic % nickel;    5-10 atomic % hafnium; and    a balance of titanium.    
   
   
       5 . A shape memory alloy, comprising: 
 25-35 atomic % nickel;    (50-Ni) atomic % platinum, where Ni is the atomic % nickel;    5-10 atomic % zirconium; and    a balance of titanium.    
   
   
       6 . A multiferroic device, comprising: 
 an active region formed from a material having a reversible phase transformation, including: 
 a first phase with a ferroelectric behavior;  
 a second phase with a ferromagnetic behavior;  
 wherein, the phase transformation from the first phase to the second phase exhibits low hysteresis;  
   an actuating system to cause transformation between the first phase and the second phase.    
   
   
       7 . The multiferroic device of  claim 6 , wherein the actuating system is chosen from a group consisting of an electric field, a magnetic field, and mechanical stress.  
   
   
       8 . A stent, comprising: 
 a metal support structure, having a constricted state and an expanded state;    wherein the support structure is formed from a shape memory alloy, the alloy including: 
 wherein a determinant of U 1  is between 0.995 and 1.005; and  
 wherein a second eigenvalue is between 0.9995 and 1.0005.  
   
   
   
       9 . The stent of  claim 10 , wherein the shape memory alloy includes: 
 49.5-52.0 atomic % titanium    2.1-25.0 atomic % copper;    (10.8−0.011 Cu 2 )±0.2 atomic % palladium, where Cu is the atomic % copper; and    a balance of nickel.    
   
   
       10 . The stent of  claim 10 , wherein the shape memory alloy includes nickel, titanium, copper, and platinum.  
   
   
       11 . A hydrogen storage device, comprising: 
 an active region formed from a material having a reversible phase transformation, including: 
 a first phase with high solubility for hydrogen;  
 a second phase with a low solubility for hydrogen, wherein the phase transformation from the first phase to the second phase exhibits low hysteresis;  
   an actuating system to cause transformation between the first phase and the second phase.    
   
   
       12 . A method of forming a material, comprising: 
 modifying crystallographic parameters of a material capable of at least partially changing from a first phase to a second phase, wherein: 
 volume change between the first phase and the second phase is reduced; and  
 a degree of interface matching is increased between the first phase and the second phase.  
   
   
   
       13 . The method of  claim 12 , further including modifying crystallographic parameters to allow for a continuum of volume fractions of pairs of variants of the second phase.  
   
   
       14 . The method of  claim 12 , wherein modifying crystallographic parameters of a material includes modifying a NiTiPdHf alloy capable of at least partially changing from austenite to martensite.  
   
   
       15 . The method of  claim 12 , wherein modifying crystallographic parameters of a material includes modifying a NiTiCuPd alloy capable of at least partially changing from austenite to martensite.  
   
   
       16 . The method of  claim 12 , wherein modifying crystallographic parameters of a material includes modifying a CuAlZnNi alloy capable of at least partially changing from austenite to martensite.  
   
   
       17 . A method of forming a material, comprising: 
 modifying crystallographic parameters of a material capable of at least partially changing from a first phase to a second phase, wherein: 
 a degree of interface matching is increased between the first phase and the second phase, and  
 a continuum of volume fractions of pairs of variants of the second phase are available.  
   
   
   
       18 . The method of  claim 17 , wherein a difference in volume between phases is maintained to accommodate selective solid solution storage of a gas.  
   
   
       19 . The method of  claim 18 , wherein the gas includes hydrogen.