FUNCTIONAL MEMBER FROM Co-BASED ALLOY AND PROCESS FOR PRODUCING THE SAME

• US 20110041966A1
• Filed: 04/07/2008
• Published: 02/24/2011
• Est. Priority Date: 10/11/2005
• Status: Active Grant

• Current Assignee: Japan Science And Technology Agency
• Original Assignee: Japan Science And Technology Agency
• Inventors: KAINUMA, Ryosuke, OMORI, Toshihiro, SUTOU, Yuji, ISHIDA, Kiyohito, YAMAUCHI, Kiyoshi
• Granted Patent: US 8,021,499 B2
• Time in Patent Office: Days
• US Class Current: 148/674
• CPC Class Codes: C22C 19/07 based on cobalt
• CPC Class Codes: C22F 1/10 of nickel or cobalt or alloys based thereon
• CPC Class Codes: C23F 1/00 Etching metallic material by chemical means manufacture of printing surfaces B41C; manufacture of printed circuits H05K
• CPC Class Codes: C23F 1/28 for etching iron group metals
• CPC Class Codes: C25F 3/22 of heavy metals

Abstract

A Co-based alloy having a fundamental composition of Co—Al binary system containing 3-15% Al and having lamellar structure wherein f.c.c. structure α-phase and β(B2)-phase are superimposed on each other in layers, which Co-based alloy is modified so as to have a porous surface layer region effective for chemical retaining capability, sustained release, biocompatibility, etc. through selective removal of either the α-phase or the β-phase from the surface layer. As a third component, at least one member selected from among Ni, Fe, Mn, Ga, Cr, V, Ti, Mo, Nb, Zr, W, Ta, Hf, Si, Rh, Pd, Ir, Pt, Au, B, C and P may be contained in a total amount of 0.001 to 60%.

Claims

1. A functional member from Co-based alloy comprising:

a base member of Co—

Al binary alloy containing 3 to 15% by mass of Al; and

a lamellar structure wherein the occupancy ratio is 30% by volume or more, a f.c.c. structure α

-phase and β

(B2)-phase with an interlayer spacing of 100 μ

m or less are repeated in layers, and the surface of the base member is modified so as to have a porous surface layer region through selective removal of the α

-phase or the β

(B2)-phase.

2. The functional member from Co-based alloy according to claim 1, further comprising a base member of a Co-based alloy having a composition which comprises, on the basis of mass percent, 3 to 15% of Al and further comprises one or more members selected

from the following:

0.01 to 50% of Ni, 0.01 to 40% of Fe, 0.01 to 30% of Mn, 0.01 to 40% of Cr, 0.01 to 30% of Mo, 0.01 to 5% of Si, 0.01 to 30% of W, 0.01 to 10% of Zr, 0.01 to 15% of Ta, 0.01 to 10% of Hf, 0.01 to 20% of Ga, 0.01 to 20% of V, 0.01 to 12% of Ti, 0.01 to 20% of Nb, 0.001 to 3% of C, 0.01 to 20% of Rh, 0.01 to 20% of Pd, 0.01 to 20% of Ir, 0.01 to 20% of Pt, 0.01 to 10% of Au, 0.001 to 1% of B, and 0.001 to 1% of P in a total of 0.001 to 60% and the balance being cobalt without inevitable impurities.

3. The functional member from Co-based alloy according to claim 1, wherein the porous surface layer region has a depth of 500 nm or more below the surface of the base member and the area of the porous surface layer region is 1.5 times more than that of the surface area before porous formation.

4. A process for producing the functional member from Co-based alloy comprising the steps of:

dissolving the Co-based alloy having the composition according to claim 1;

cooling with an average cooling rate;

500°

C./min or less in the range of 1500 to 600°

C. so as to form the lamellar structure in which the f.c.c. structure α

-phase and B2-type of β

-phase, the L1₂-type γ

′

phase, the D0₁₉-type precipitate, and/or the M₂₃C₆-type carbide are repeated in layers and the occupancy ratio is 30% by volume or more;

selectively removing either the α

-phase or the B2-type of β

-phase, or any of the L1₂-type γ

′

phase, D0₁₉-type precipitate, and/or M₂₃C₆-type carbide from the surface layer region of the Co-based alloy; and

modifying the depth of 500 nm or more below the surface of the base member to form the porous surface layer region so that the area of the porous surface layer region is 1.5 times more than that of the surface area before porous formation.

5. A process for producing the functional member from Co-based alloy comprising the steps of:

solution-treating the Co-based alloy having the composition according to claim 1 at 900 to 1400°

C.;

aging-treating at 500 to 900°

C. so as to form the lamellar structure wherein the f.c.c. structure α

-phase and B2 type of β

-phase, the L1₂-type γ

′

phase, the D0₁₉-type precipitate, and/or the M₂₃C₆-type carbide are repeated in layers and the occupancy ratio of the whole metallic structure is 30% by volume or more;

selectively removing either the α

-phase or the B2-type of β

-phase, or any of the L1₂-type γ

′

phase, D0₁₉-type precipitate, and/or M₂₃C₆-type carbide from the surface layer region of the Co-based alloy; and

modifying the depth of 500 nm or more below the surface of the base member to form the porous surface layer region so that the area of the porous surface layer region is 1.5 times more than that of the surface area before porous formation.

6. The process according to claim 4, wherein either the α

-phase or the B2-type of β

-phase, or any of the L1₂-type γ

′

phase, D0₁₉-type precipitate, and/or M₂₃C₆-type carbide is selectively removed by physical polishing, chemical polishing, or electrochemical polishing.