Claims

1. A precision gear whose module is 0.2 or less, formed of a metallic material comprising an amorphous metal structure having a volume ratio of 50% or more.

2. A precision gear whose module is 0.2 or less, formed of a metallic material comprising an amorphous metal structure and nanocrystals of 100 nm or less in the amorphous metal structure.

3. A precision gear according to claim 1 or 2, wherein the precision gear has at least one of two properties including a Vickers hardness of Hv 500 (equivalent to Rockwell hardness of HRC 49) or more and a tensile strength of 1500 MPa or more.

4. A precision gear according to any one of claims 1 to 3, wherein the precision gear has a surface roughness of 2 μm Ry or less.

5. A precision gear according to any one of claims 1 to 4, wherein the precision gear is a sun carrier which comprises a sun gear and a carrier plate.

6. A gear mechanism comprising the precision gear according to any one of claims 1 to 5.

7. A gear mechanism according to claim 6, wherein the gear mechanism comprises a planetary gear reduction system.

8. A precision gear according to any one of claims 1 to 5, wherein the metallic material has a composition represented by the formula of M_{100-nTM.sub.n} (in which M is one or more elements selected from the group consisting of Fe, Co, Ni, Cu, Ti, Zr and Hf; TM always includes at least 1 atomic percent, one or more elements selected from the group consisting of Cr. Mo, Nb, Al, Sn and B; the balance comprises transition metal elements selected from the group consisting of Groups 3, 4, 5, 6, 8, 9, 10 and 11 (except for Cr, Mo, Nb and the elements employed for the M) and typical elements selected from the group consisting of Groups 13, 14 and 15 (except for Al, Sn and B); and n is between 5 atomic percent and 50 atomic percent).

9. A precision gear according to any one of claims 1 to 5, wherein the metallic material has a composition represented by the formula of Cu_{pTi.sub.qM1.sub.100-p-q} (in which M1 is one or more elements selected from the group consisting of Hf, Zr, iron group elements, platinum group elements and noble metals (Group 11), Al, Sn and Zn; p is between 50 atomic percent and 65 atomic percent; and q is between 2 atomic percent and 20 atomic percent).

10. A precision gear according to any one of claims 1 to 5, wherein the metallic material has a composition represented by the formula of Ni_{100-s-t-uNb.sub.s}(Zr, Hf)_tM2.sub.u (in which M2 is one or more elements selected from the group consisting of Ti, iron group elements, platinum group elements, noble metals (Group 11); s is between 10 atomic percent and 25 atomic percent; t is between 5 atomic percent and 20 atomic percent; u is between 5 atomic percent and 25 atomic percent; and the sum of the t and u is between 10 atomic percent and 35 atomic percent).

11. A precision gear according to any one of claims 1 to 5, wherein the metallic material has a composition represented by the formula of Fe_{100-x-yM3.sub.xM4.sub.y} (in which M3 is one or more elements selected from the group consisting of transition metal elements in Groups 3, 4, 5 and 6; M4 is one or more elements selected from the group consisting of Mn, Ru, Rh, Pd, Ga, Al, Ge, Si, B and C; x is between 2 atomic percent and 35 atomic percent, and y is between 5 atomic percent and 30 atomic percent).

12. A precision gear according to any one of claims 1 to 5, wherein the metallic material has a composition represented by the formula of (Fe_1-a(Co, Ni)_a)_{100-x-yM3.sub.xM4.sub.y} (in which M3 is one or more elements selected from the group consisting of transition metal elements in Groups 3, 4, 5 and 6; M4 is one or more elements selected from the group consisting of Mn, Ru, Rh, Pd, Ga, Al, Ge, Si B and C; a is between 0.1 and 0.7; x is 2 atomic percent and 35 atomic percent; and y is between 5 atomic percent and 30 atomic percent).

13. A precision gear according to claim 11 or 12, wherein the M4 always includes B.

14. A precision gear according to any one of claims 1 to 5, wherein the metallic material has a composition represented by the formula of (Zr, Hf)_{aM5.sub.bM6.sub.c} (in which M5 is one or more elements selected from the group consisting of elements in Groups 3, 5, 6, iron group elements, platinum group elements, noble metals (Group 11), Ti and Mn; M6 is one or more elements selected from the group consisting of Be, Zn, Al, Ga, B, C and N; a is between 30 atomic percent and 70 atomic percent; b is between 15 atomic percent and 65 atomic percent; and c is between 1 atomic percent and 30 atomic percent).

15. A precision gear according to any one of claims 1 to 5, wherein the metallic material has a composition represented by the formula of Ti_{100-i-j-kCu.sub.iM7.sub.jM8.sub.k} (in which M7 is one or more transition metal elements selected from the group consisting of Zr, Hf, iron group elements and platinum group elements; M8 is one or more elements selected from the group consisting of elements in Groups 3, 5 and 6, Al, Sn, Ge, Si, B and Be; i is between 5 atomic percent and 35 atomic percent; j is between 10 atomic percent and 35 atomic percent; and k is between 1 atomic percent and 20 atomic percent).

16. A precision gear according to any one of claims 1 to 5, wherein the precision gear is formed at a cooling rate of between 300° C./second and 10^7° C./second.

17. A method for manufacturing a precision gear, wherein the precision gear according to any one of claims 1 to 15 is formed by injection molding of molten metal which is represented by a die casting process.

18. A method for manufacturing a precision gear, wherein the precision gear according to any one of claims 1 to 15 is formed by a superplastic forging process in a viscous fluid temperature.