Fabrication of high temperature low hysterisis shape memory alloy thin film

Abstract

A nickel titanium hafnium copper thin film shape memory alloy having a composition (TiHf) 5-55 (NiCu) 45-50 comprising about 2 atomic percent to about 10 atomic percent copper and the fabrication method of said shape memory thin film by magnstron sputtering using Kr as working gas and conducting the deposition at elevated substrate temperature.

We claim  
     
         1 . A nickel titanium hafnium copper thin film shape memory alloy having a composition (TiHf) 50-55 (NiCu) 45-50  comprising about 2 atomic percent to about 10 atomic percent copper.  
     
     
         2 . The nickel titanium hafnium copper thin film shape memory alloy composition of  claim 1  comprising about 6 atomic percent to about 10 atomic percent copper.  
     
     
         3 . The shape memory alloy thin film composition of  claim 1  wherein the combined nickel and copper content is about 48 to 50 atomic percent.  
     
     
         4 . The shape memory alloy thin film of  claim 1  wherein the hafnium content is about 5 to 25 atomic percent.  
     
     
         5 . The shape memory alloy thin film of  claim 4  wherein the hafnium content is about 10 to 20 atomic percent.  
     
     
         6 . The shape memory alloy thin film of  claim 5  wherein the combined TiHf content is about 50 to 52 atomic percent  
     
     
         7 . A magnetron sputter deposition process for producing a (NiCu)(TiHf) thin film alloy exhibiting shape memory characteristics comprising: 
 conducting the deposition using krypton as process gas; and,    heating a substrate onto which the thin film alloy is deposited to maintain a temperature ranging from about 350 ° C. to about 500° C. during said deposition.    
     
     
         8 . The process of  claim 7  using a hot pressed powder sputter target comprising components selected from the group consisting of nickel, titanium, hafnium, and copper in proportions so as to produce a thin film alloy having a composition (TiHf) 50-55 (NiCu) 45-50  comprising about 2 atomic percent to about 10 atomic percent copper.  
     
     
         9 . A magnetron sputter deposition process for producing a thin film alloy exhibiting shape memory characteristics comprising: 
 conducting the deposition using krypton as process gas;    heating a substrate onto which the thin film alloy is deposited to maintain a temperature ranging from about 350 ° C. to about 500° C. during said deposition; and,    using a hot pressed powder sputter target comprising components selected from the group consisting of nickel, titanium, hafnium, and copper in proportions so as to produce a thin film alloy having a composition (TiHf) 50-55 (NiCu) 45-50  comprising about 2 atomic percent to about 10 atomic percent copper.    
     
     
         10 . The process of  claim 9  comprising using a hot pressed powder sputter target comprising components selected from the group consisting of nickel, titanium, hafnium, and copper in proportions so as to produce a thin film alloy having a composition (TiHf) 50-55 (NiCu) 45-50  comprising about 2 atomic percent to about 10 atomic percent copper and about 5 atomic percent to about 25 atomic percent hafnium.  
     
     
         11 . The process of  claim 10  comprising using a hot pressed powder sputter target comprising components selected from the group consisting of nickel, titanium, hafnium, and copper in proportions so as to produce a thin film alloy having a composition (TiHf) 50-25 (NiCu) 48-50  comprising about 6 atomic percent to about 10 atomic percent copper and about 5 atomic percent to about 25 atomic percent hafnium.