Cobalt-based alloy product and method for producing cobalt-based alloy product
The present invention relates to a Co-based alloy product including a polycrystal of a Co-based alloy, the Co-based alloy including: 0.001 mass %≤C<0.100 mass %; 9.0 mass %≤Cr<20.0 mass %; 2.0 mass %≤Al<5.0 mass %; 13.0 mass %≤W<20.0 mass %; and 39.0 mass %≤Ni<55.0 mass %, with the balance being Co and unavoidable impurities, in which the Co-based alloy product comprises segregated cells formed inside a crystal grain of the polycrystal, the segregated cells have an average size of 1 μm or larger and 100 μm or smaller, and the segregated cells contain Al and Cr, and a method for producing the Co-based alloy product.
1. A Co-based alloy product, comprising:
a polycrystal of a Co-based alloy;
a γ phase that is a matrix phase inside a crystal grain of the polycrystal;
segregated cells formed inside the crystal grain of the polycrystal in the γ phase that is a matrix phase, wherein the segregated cells have an average size of 1 μm or larger and 100 μm or smaller and contain Al and Cr of the Co-based alloy; and
a γ′ phase coherently precipitated inside the crystal grain of the polycrystal,
wherein the Co-based alloy comprises a composition by mass % of:
0.001 mass %≤C<0.100 mass %;
13.5 mass %≤Cr<20.0 mass %;
2.0 mass %≤Al<5.0 mass %;
13.0 mass %≤W<20.0 mass %; and
39.0 mass %≤Ni<55.0 mass %,
with the balance being Co and unavoidable impurities.
2. The Co-based alloy product according to claim 1 , wherein the Co-based alloy further comprises at least one element selected from the group consisting of:
Mo≤3.0 mass %;
Nb≤2.0 mass %;
Ti≤2.0 mass %; and
Ta≤2.0 mass %.
3. The Co-based alloy product according to claim 2 , wherein the Co-based alloy further comprises at least one element selected from the group consisting of:
0.001 mass %≤B<0.020 mass %;
0.0001 mass %≤Zr<0.010 mass %;
Mg≤0.10 mass %; and
Ca≤0.20 mass %.
4. The Co-based alloy product according to claim 3 , having a 0.2% proof stress at 800° C. of 650 MPa or higher.
5. The Co-based alloy product according to claim 3 , having a tensile strength at 800° C. of 850 MPa or higher.
6. The Co-based alloy product according to claim 2 , having a 0.2% proof stress at 800° C. of 650 MPa or higher.
7. The Co-based alloy product according to claim 2 , having a tensile strength at 800° C. of 850 MPa or higher.
8. The Co-based alloy product according to claim 1 , wherein the Co-based alloy further comprises at least one element selected from the group consisting of:
0.001 mass %≤B<0.020 mass %;
0.0001 mass %≤Zr<0.010 mass %;
Mg≤0.10 mass %; and
Ca≤0.20 mass %.
9. The Co-based alloy product according to claim 8 , having a 0.2% proof stress at 800° C. of 650 MPa or higher.
10. The Co-based alloy product according to claim 8 , having a tensile strength at 800° C. of 850 MPa or higher.
11. The Co-based alloy product according to claim 1 , having a 0.2% proof stress at 800° C. of 650 MPa or higher.
12. The Co-based alloy product according to claim 1 , having a tensile strength at 800° C. of 850 MPa or higher.
13. The Co-based alloy product according to claim 1 , wherein the inside of the segregated cell comprises Co, Ni and W, and the boundary of the segregated cell comprises Al and Cr.