Patent ID: 8808618

Claim:
A method for forming an expandable medical device comprising the steps of: a) forming a rod or tube having a surface and an original outer cross-sectional area, said rod or tube being formed of a metal alloy, said metal alloy including two or more metals selected from the group consisting of calcium, chromium, cobalt, copper, gold, iron, lead, magnesium, molybdenum, nickel, niobium, platinum, rare earth metals, rhenium, silver, tantalum, titanium, tungsten, yttrium, zinc, and zirconium, said metal alloy including at least one metal selected from the group consisting of molybdenum, rhenium, tantalum, tungsten; b) drawing down said outer cross-sectional area of said rod or tube to a first drawn down cross-sectional area by a reducing mechanism, said rod or tube being drawn down at least once to obtain said first drawn down cross-sectional area, said outer cross-sectional area being reduced by no more than about 25% during each drawing down process; c) annealing said rod or tube during a first annealing step prior to said rod or tube having said original outer cross-sectional area drawn down by more than about 60%, said step of annealing performed at a first annealing temperature when said rod or tube is at said first drawn down cross-sectional area; d) drawing down said cross-sectional area of said rod or tube from said first drawn down cross-sectional area to a second drawn down cross-sectional area by the reducing mechanism after said rod or tube has been annealed, said second drawn down cross-sectional area smaller than said first drawn down cross-sectional area, said rod or tube being drawn down at least once to obtain said second drawn down cross-sectional area, said outer cross-sectional area reduced by no more than about 25% during each drawing down process; e) annealing said rod or tube during a second annealing step prior to said rod or tube having said first drawn down cross-sectional area being drawn down by more than about 60%, said step of annealing performed at a second annealing temperature when said rod or tube is at said second drawn down cross-sectional area, said second annealing temperature lower temperature than said first annealing temperature; f) controlling an atmosphere about said rod or tube during said steps of drawing and annealing so that said metal alloy of said rod or tube after final drawing and annealing steps includes less than about 30 ppm nitrogen, less than about 200 ppm carbon, and less than about 150 ppm oxygen; and, g) repeating steps d, e and f until said tube is at a desired thickness.