Ni-Ti SERIES SHAPE MEMORY ALLOY WIRE ROD AND ITS PRODUCING METHOD

摘要

PROBLEM TO BE SOLVED: To produce an N-Ti series shape memory alloy wire rod relatively low in the raw material cost, moreover excellent in durability in spite of fine wire of <=0.2 mm and furthermore excellent in workability when thinned and to provide a method for producing the same. SOLUTION: An alloy raw material is blended and melted in such a manner that an alloy composition in which the content of Ti is controlled to 40 to 50 atomic %, the content of Ni is controlled to 42 to 51 atomic %, and the content of at least either Zr or Hf is controlled to 3 to 16 atomic % in total is prepared. Then, while the molten metal is jetted from a jetting nozzle 2 having the pore size of <=0.2 mm, the same is cooled and solidified in a cooling gas to obtain an Ni-Ti series shape memory alloy wire rod W formed into the wire diameter of <=0.2 mm and in which the maximum size of crystal grains in the axial orthogonal cross-section is 1 to 15μm.