Processable high thermal neutron absorbing Fe-base alloy powder
A corrosion resistant, neutron absorbing, austenitic alloy powder is disclosed having the following composition in weight percent. C 0.08 max. Mn up to 3 Si up to 2 P 0.05 max. S 0.03 max. Cr 17-27 Ni 11-20 Mo + (W/1.92) up to 5.2 B Eq 0.78-13.0 O 0.1 max. N up to 0.2 Y less than 0.005 The alloy contains at least about 0.25% B, at least about 0.05% Gd, and the balance of the alloy composition is iron and usual impurities. B Eq is defined as % B+4.35×(% Gd). An article of manufacture made from consolidated alloy powder is also disclosed which is characterized by a plurality of boride and gadolinide particles dispersed within a matrix. The boride and gadolinide particles are predominantly M 2 B, M 3 B 2 , M 3 X, and M 5 X in form, where X is gadolinium or a combination of gadolinium and boron and M is one or more of the elements silicon, chromium, nickel, molybdenum, iron.
1. A corrosion resistant, thermal neutron absorbing alloy powder having the following composition in weight percent,
Carbon
not more than about 0.08
Manganese
up to about 3
Silicon
up to about 2
Chromium
about 17 to about 27
Nickel
about 11 to about 20
Mo + (W/1.92)
up to about 5.2
Boron
at least about 0.25
Gadolinium
at least about 0.05
Oxygen
about 0.01 to about 0.1
Nitrogen
up to 0.2
wherein B Eq =% boron+(4.35×% gadolinium), 0.78≦B Eq ≦13.0, and the balance of the alloy powder composition is iron and usual impurities, wherein the impurities include 0.05% max. phosphorus, 0.03% max. sulfur, less than 0.005% yttrium, and less than 0.01% aluminum.
2. An alloy powder as claimed in claim 1 which contains not more than about 2.6% gadolinium.
3. An alloy powder as claimed in claim 1 which contains not more than about 2.5% boron.
4. An alloy powder as claimed in claim 1 wherein Mo+(W/1.92) is at least about 2.8%.
5. An alloy powder as claimed in claim 1 wherein Mo+(W/1.92) is not more than about 0.5%.
6. An alloy powder as claimed in claim 1 which contains not more than about 1.0% boron and B Eq is not more than about 12.0%.
7. An alloy powder as claimed in claim 1 which contains not more than about 2.0% boron.
8. An alloy powder as claimed in claim 7 which contains not more than about 0.25% gadolinium.
9. An alloy powder as claimed in claim 1 which contains at least about 0.12% gadolinium.
10. An alloy powder as claimed in claim 9 which contains not more than about 2.6% gadolinium.
11. An alloy powder as claimed in claim 1 which contains at least about 300 ppm nitrogen.
12. An alloy powder as claimed in claim 1 which contains not more than about 0.05% carbon.
13. An article of manufacture that provides good processability in combination with good mechanical and corrosion resistance properties, said article being formed from consolidated austenitic alloy powder having the following composition in weight percent,
Carbon
not more than about 0.08
Manganese
up to about 3
Silicon
up to about 2
Chromium
about 17 to about 27
Nickel
about 11 to about 20
Mo + (W/1.92)
up to about 5.2
Boron
at least about 0.25
Gadolinium
at least about 0.05
Oxygen
about 0.01 to about 0.1
Nitrogen
up to 0.2
wherein B Eq =% boron+(4.35×% gadolinium), 0.78≦B Eq ≦13.0, and the balance of the alloy powder composition is iron and usual impurities, wherein the impurities include 0.05% max. phosphorus, 0.03% max. sulfur, less than 0.005% yttrium, and less than 0.01% aluminum, and the article comprises a matrix and a plurality of boride and gadolinide particles dispersed within the matrix, said boride and gadolinide particles are predominantly M 2 B, M 3 B 2 , M 5 X, and M 3 X in form, where X is gadolinium or a combination of gadolinium and boron and M is one or more of the elements silicon, chromium, nickel, molybdenum, and iron.
14. An article as claimed in claim 13 wherein the alloy powder contains not more than about 0.05% carbon.
15. An article as claimed in claim 13 wherein the alloy powder contains at least about 0.12% gadolinium.
16. An article as claimed in claim 15 wherein the alloy powder contains not more than about 2.6% gadolinium.
17. An article as claimed in claim 13 wherein the alloy powder contains not more than about 2.0% boron.
18. An article as claimed in claim 13 wherein % Mo+(% W/1.92) in the alloy powder is at least about 2.8%.
19. An article as claimed in claim 13 wherein % Mo+(% W/1.92) in the alloy powder is not more than about 0.5%.
20. An article as claimed in claim 13 wherein the alloy powder contains not more than about 1.0% boron and B Eq is not more than about 12.0%.
21. An article as claimed in claim 20 wherein the average area fraction of the borides and gadolinides is not more than about 20%.
22. An article as claimed in claim 13 wherein the average area fraction of the borides and gadolinides is not more than about 22% and the alloy powder contains not more than about 2% boron and not more than about 0.25% gadolinium.
23. An article as claimed in claim 13 wherein the alloy powder contains not more than about 1.0% boron.
24. An article as claimed in claim 23 wherein the alloy powder contains at least about 0.12% gadolinium.
25. An article as claimed in claim 24 wherein the alloy powder contains not more than about 2.6% gadolinium.