HIGH STRENGTH VACUUM DEPOSITED NITIONOL ALLOY FILMS, MEDICAL THIN FILM GRAFT MATERIALS AND METHOD OF MAKING SAME

摘要

The present invention relates to an implantable medical graft and a method of making the same by physical vapor deposition processes. The graft is comprised of a microporous thin-film member having a plurality of openings and a structural support element underlying and physically attached to the microporous thin-film member, the microporous thin-film member has either shape memory or superelastic properties without having to be heat treated to set the transition temperature for the material. A vacuum deposition method is provided for fabricating the inventive microporous thin-film member and other high-strength nitinol films by sputter depositing nickel and titanium from a heated sputtering target, and controlling the sputter deposition process parameters in order to create high-strength nitinol films that exhibit shape memory and/or superelastic properties without the need for precipitation annealing to attenuate the transition conditions of the deposited material. A vacuum deposited nitinol film having high-strength properties equal to or better than wrought nitinol films, which are characterized by having non-columnar crystal grain structures, and which are deposited in either the martensitic state with high transition temperature values to behave martensitically in vivo, in the austenitic state with low transition temperature values to behave austenitically in vivo, or in the martensitic state with transition temperatures near body temperature to behave austenitically in vivo.