Patent ID: 9539372
Date: 2017-01-10
CPC Classifications: A61L,C22C,C30B

Claim:
1. A method of forming a biocompatible anisotropic, single crystal copper-aluminum shape memory alloy having hyperelastic properties, the anisotropic single crystal shape memory alloy material formed being deformable at a constant force at recoverable strain of at least 9% with a very narrow loading-unloading hysteresis, a recovery which is completely repeatable and complete and a very low yield strength when martensitic, the method comprising the steps of: forming a single crystal copper-aluminum-based shape memory alloy from a seed of copper aluminum based alloy aligned on the <100> crystallographic direction; in a surface region of depth greater than 1 nm below an exposed outer surface of the single crystal copper-aluminum-based shape memory alloy, diffusing aluminum atoms into the surface region to enrich the surface region in aluminum relative to copper; and forming a controlled layer of aluminum oxide on the single crystal copper-based shape memory alloy by oxidizing the aluminum atoms in the surface region.