Shape memory alloy with ductility and a making process of the same

Abstract

A Ti—Ni shape memory alloy with ductility, including Ti of 50˜66 atomic % in a composition, and in which precipitation of Ti 2 Ni phases at grain boundaries is suppressed.

1 . A Ti—Ni shape memory alloy composition comprising Ti in an amount of 50-66 atomic % of said composition, and wherein the Ti—Ni shape memory alloy composition is ductile and wherein precipitation of Ti 2 Ni phases at grain boundaries is suppressed.  
   
   
       2 . The Ti—Ni shape memory alloy composition as claimed in  claim 1 , wherein the Ti—Ni shape memory alloy composition exhibits plastic strain of not less than 15% at room temperature.  
   
   
       3 . The Ti—Ni shape memory alloy composition as claimed in  claim 1 , wherein the Ti—Ni shape memory alloy composition is produced as a thin film.  
   
   
       4 . The Ti—Ni shape memory alloy composition as claimed in  claim 2 , wherein the Ti—Ni shape memory alloy composition is produced as a thin film.  
   
   
       5 . A process of making the Ti—Ni shape memory alloy composition as claimed in  claim 1 , which process comprises crystallizing an amorphous Ti—Ni alloy at 600-900K for less than an hour and then cooling down to room temperature slowly in order to suppress precipitation of Ti 2 Ni phases at grain boundaries.  
   
   
       6 . The process as claimed in  claim 5 , wherein crystallization is conducted at 800-900K for less than 10 minutes.  
   
   
       7 . The process as claimed in  claim 5 , wherein the Ti—Ni shape memory alloy composition is produced as a thin film.  
   
   
       8 . The process as claimed in  claim 6 , wherein the Ti—Ni shape memory alloy composition is produced as a thin film.  
   
   
       9 . The Ti—Ni shape memory alloy composition as claimed in  claim 1 , which comprises Ti and Ni.  
   
   
       10 . The Ti—Ni shape memory alloy composition as claimed in  claim 9 , wherein one or more elements other than Ti and Ni is added or mixed as an impurity.  
   
   
       11 . The Ti—Ni shape memory alloy composition as claimed in  claim 10 , wherein said element(s) is/are in an amount which preserves crystalline structures of Ti 2 Ni and TiNi phases.