US 7,371,295 B2
	Shape memory alloy and method for producing same
Katsunari Oikawa, Shibata-gun (Japan); Kiyohito Ishida, 15-41-503, Ichibancho 1-chome, Aoba-ku, Sendai-shi, Miyagi-ken (Japan); Ryosuke Kainuma, Natori (Japan); Yuuki Tanaka, Sendai (Japan); Masahiro Ohta, Wako (Japan); and Toru Sukigara, Wako (Japan)
Assigned to Honda Motor Co., Ltd., Tokyo (Japan); Kiyohito Ishida, Fukuoka (Japan); and National Institute of Advanced Industrial Science & Technology, Tokyo (Japan)
Filed on Mar. 18, 2004, as Appl. No. 10/804,244.
Claims priority of application No. 2003-074502 (JP), filed on Mar. 18, 2003.
Prior Publication US 2005/0016642 A1, Jan. 27, 2005
Int. Cl. C22C 30/00 (2006.01)

U.S. Cl. 148—402  [148/442; 420/580]

5 Claims

1. A shape memory alloy comprising Co, Ni and Al, wherein said shape memory alloy has a two-phase structure comprising a β-phase having a B2 structure and a γ-phase having an fcc structure, at least 40% by area of crystal grain boundaries of said β-phase being occupied by said γ-phase and the fraction of said γ-phase volume in said shape memory alloy being 5 to 50% by volume, wherein said alloy contains 23 to 27 atomic % of Al and 39 to 45 atomic % of Co, the balance being 28 to 38 atomic % of Ni and inevitable impurities, and wherein said alloy has a tensile strength of about 400-1100 MPa and a shape recovery of 18% or more.