EP0359446A1 — High strength, low modulus titanium alloy

Claim 1

Independent Claim 214 words

A high strength, low modulus, ductile, biocompatible titanium base alloy consisting of the following alloying components: - an amount up to 24% by weight of at least one isomorphous beta stabilizer selected from the group consisting of molybdenum, tantalum, niobium and zirconium, provided that molybdenum, when present, is in an amount of at least 10% by weight, and when molybdenum is present with zirconium the molybdenum is in an amount of 10 to 13% by weight and the zirconium is in an amount of 5 to 7% by weight; an amount up to 3.0% by weight of at least one eutectoid beta stabilizer selected from the group consisting of iron, manganese, chromium, cobalt and nickel, wherein the combined amount of isomorphous beta stabilizer and eutectoid beta stabilizer is at least 10.2% by weight; optionally an amount up to 3.0% by weight of at least one metallic alpha stabilizer selected from the group consisting of aluminum and lanthanum; and the balance titanium, apart from incidental impurities, but not exceeding by weight, among the non-metallic alpha stabilizers, 0.05% carbon, 0.30% oxygen and 0.02% nitrogen; and not exceeding 0.02% of the eutectoid former hydrogen; the proportion of each of the alloying components being balanced to provide an alloy having a modulus of elasticity not exceeding 100 GPa.

Claim 2

Dependent Claim 214 words

A high strength, low modulus, ductile, biocompatible titanium base alloy consisting of the following alloying components: - an amount up to 24% by weight of at least one isomorphous beta stabilizer selected from the group consisting of molybdenum, tantalum, niobium and zirconium, provided that molybdenum, when present, is in an amount of at least 10% by weight, and when molybdenum is present with zirconium the molybdenum is in an amount of 10 to 13% by weight and the zirconium is in an amount of 5 to 7% by weight; an amount up to 3.0% by weight of at least one eutectoid beta stabilizer selected from the group consisting of iron, manganese, chromium, cobalt and nickel, wherein the combined amount of isomorphous beta stabilizer and eutectoid beta stabilizer is at least 10.2% by weight; optionally an amount up to 3.0% by weight of at least one metallic alpha stabilizer selected from the group consisting of aluminum and lanthanum; and the balance titanium, apart from incidental impurities, but not exceeding by weight, among the non-metallic alpha stabilizers, 0.05% carbon, 0.30% oxygen and 0.02% nitrogen; and not exceeding 0.02% of the eutectoid former hydrogen; the proportion of each of the alloying components being balanced to provide an alloy having a modulus of elasticity not exceeding 100 GPa.

Claim 3

Dependent Claim 63 words

An alloy according to claim 1, having a modulus of elasticity of 66.9 to 100 GPa; a .2% offset yield strength of 925 to 1221 MPa; a rotating beam fatigue strength of 483 to 621 MPa at 10⁷ cycles and of 345 to 380 MPa at a stress concentration factor, K t , of 1.6; and a tensile elongation of at least 10%.

Claim 4

Dependent Claim 44 words

An alloy according to claim 1, consisting of 10 to 13% by weight of molybdenum; 5 to 7% by weight of zirconium; 0.2 to 3.0% by weight of iron; 0 to 3.0% by weight of aluminum; and the balance titanium, apart from incidental impurities.

Claim 5

Dependent Claim 41 words

An alloy according to claim 3 consisting of about 11.5% by weight molybdenum, about 6.0% by weight zirconium; about 0.4 to about 2.0% by weight iron, 0 to about 1.0% by weight aluminum; and the balance titanium, apart from incidental impurities.

Claim 6

Dependent Claim 39 words

An alloy according to claim 1, consisting of 10.0 to 20.0% by weight niobium; 1.0 to 4.0% by weight zirconium; about 2.0% by weight iron; up to 1.0% by weight aluminum; and the balance titanium, apart from incidental impurities.

Claim 7

Independent Claim 179 words

A method for preparing a high strength, low modulus, ductile titanium base alloy which comprises mechanically blending particles of the following alloying components: - an amount up to 24 % by weight of at least one isomorphous beta stabilizer selected from the group consisting of molybdenum, tantalum, niobium and zirconium; an amount up to 3.0% by weight of at least one eutectoid beta stabilizer selected from the group consisting of iron, manganese, chromium, cobalt and nickel; optionally an amount up to 3.0% by weight of at least one metallic alpha stabilizer selected from the group consisting of aluminum and lanthanum; and the balance titanium; introducing the resulting blended feedstock into a plasma arc furnace wherein the blend is melted to form a homogeneous melt, allowing the melt to cool and solidify, vacuum arc remelting the resulting solid to assure that the hydrogen content does not exceed 0.02% by weight and thermomechanically processing the resulting solid at a temperature within the range of 710° to 1038° C. to provide an alloy having a modulus of elasticity not exceeding 100 GPa.

Claim 8

Independent Claim 179 words

A method for preparing a high strength, low modulus, ductile titanium base alloy which comprises mechanically blending particles of the following alloying components: - an amount up to 24 % by weight of at least one isomorphous beta stabilizer selected from the group consisting of molybdenum, tantalum, niobium and zirconium; an amount up to 3.0% by weight of at least one eutectoid beta stabilizer selected from the group consisting of iron, manganese, chromium, cobalt and nickel; optionally an amount up to 3.0% by weight of at least one metallic alpha stabilizer selected from the group consisting of aluminum and lanthanum; and the balance titanium; introducing the resulting blended feedstock into a plasma arc furnace wherein the blend is melted to form a homogeneous melt, allowing the melt to cool and solidify, vacuum arc remelting the resulting solid to assure that the hydrogen content does not exceed 0.02% by weight and thermomechanically processing the resulting solid at a temperature within the range of 710° to 1038° C. to provide an alloy having a modulus of elasticity not exceeding 100 GPa.

Claim 9

Dependent Claim 68 words

A method according to claim 6, in which the resulting alloy has a modulus of elasticity of 66.9 to 100 GPa; a .2% offset yield strength of 925 to 1221 MPa; a rotating beam fatigue strength of 483 to 621 MPa at 10⁷ cycles and of 345 to 380 MPa at a stress concentration factor, k t , of 1.6; and a tensile elongation of at least 10%.

Claim 10

Dependent Claim 43 words

A method according to claim 6, in which the metal ingredients of the feedstock comprise 10 to 13% by weight molybdenum; 5 to 7% by weight zirconium; 0.2 to 3.0% by weight iron; 0 to 3.0% by weight aluminum; and the balance titanium.

Claim 11

Dependent Claim 42 words

A method according to claim 6, in which the metal ingredients of the feedstock comprise 10.0 to 20.0% by weight niobium; 1.0 to 4.0% by weight zirconium; about 2.0% by weight iron; up to 1.0% by weight aluminum; and the balance titanium.

Claim 12

Dependent Claim 18 words

A prosthesis made from a high strength, low modulus, ductile, biocompatible titanium base alloy according to claim 1.

High strength, low modulus titanium alloy

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