Prosthesis formed from dispersion strengthened cobalt-chromium-molybdenum alloy produced by gas atomization

Claim 1

A prosthesis made by forging a high-strength, corrosion-resistant, high temperature stable, ductile alloy having homogeneously distributed dispersed oxides and fine, equiaxed grain structure after high temperature exposure, said alloy being produced by gas atomisation and consisting essentially of the following percentage composition by weight: ______________________________________ chromium 26 to 30 molybdenum 5 to 7 manganese 0 to 1 silicon 0 to 1 iron 0 to 0.75 nickel 0 to 1.0 carbon 0 to 0.35 nitrogen 0 to 0.25 oxygen 0.003 to 0.20 oxide-forming metal 0.003 to 2.0 ______________________________________ and the balance cobalt, apart from trace amounts of incidental impurities; in which the oxide-forming metal is a metal selected from the group consisting of magnesium, calcium, aluminum, yttrium, lanthanum, titanium and zirconium, which forms high temprature-stable, non-accretive, fine oxide particles which oxide has a free energy of formation greater than the oxide of the matrix metal and is homogeneously distributed in the dispersed phase; and said alloy after fabrication by gas atomization, thermomechanical processing and further high temperature exposure has an ultimate tensile strength of 160-200 k.s.i., a 0.2% offset yield strength of 75-100 k.s.i., an elongation of 37 to 60%, and a fatigue strength at 10 7 cycles of 70-95 k.s.i.