Methods of fabricating structures, such as parts for use in nuclear power generation systems, are described herein. A representative method of fabricating a part for a nuclear reactor system includes coating a plurality of particles of a powder of a first material with a second material, and then pressing and/or heating the coated powder into a monolithic structure. The second material can be substantially solidly insoluble with the first material such that, after pressing and/or heating, the particles of the first material define grains of the monolithic structure and the second material substantially encapsulates the grains in the monolithic structure. The first material can be susceptible to corrosion by a select process, and the second material can be resistant to corrosion by the select process such that the bulk first material of the monolithic structure is resistant to corrosion by the select process.

Methods of fabricating structures, such as parts for use in nuclear power generation systems, are described herein. A representative method of fabricating a part for a nuclear reactor system includes coating a plurality of particles of a powder of a first material with a second material, and then pressing and/or heating the coated powder into a monolithic structure. The second material can be substantially solidly insoluble with the first material such that, after pressing and/or heating, the particles of the first material define grains of the monolithic structure and the second material substantially encapsulates the grains in the monolithic structure. The first material can be susceptible to corrosion by a select process, and the second material can be resistant to corrosion by the select process such that the bulk first material of the monolithic structure is resistant to corrosion by the select process.

A heat-resistant alloy contains at least one element selected from a group consisting of Al, Ti, Ni, Cr, and Mo, O, and Y, and a ratio of a content of Y in terms of mass to a content of O in terms of mass is 0.5 or greater and 100 or less.

A heat-resistant alloy contains at least one element selected from a group consisting of Al, Ti, Ni, Cr, and Mo, O, and Y, and a ratio of a content of Y in terms of mass to a content of O in terms of mass is 0.5 or greater and 100 or less.

A 3D-printed reflective optic providing very high specific stiffness through the utilization of a hollow shelled design, with closed back, filled with high-stiffness internal volumetric space-filling open-cell lattice structures. High-stiffness, structurally-integrated, sacrificial structures are also included for the purposes of reduction or elimination of tooling during post-processing operations.

A 3D-printed reflective optic providing very high specific stiffness through the utilization of a hollow shelled design, with closed back, filled with high-stiffness internal volumetric space-filling open-cell lattice structures. High-stiffness, structurally-integrated, sacrificial structures are also included for the purposes of reduction or elimination of tooling during post-processing operations.

Systems and methods discussed herein relate to Zintl-type thermoelectric materials, including a p-type thermoelectric material according to the formula AM.sub.yX.sub.y, and includes at least one of calcium (Ca), europium (Eu), ytterbium (Yb), and strontium (Sr), and has a ZT of the above about 0.60 above 675K. The n-type thermoelectric component includes magnesium (Mg), tellurium (Te), antimony (Sb), and bismuth (Bi) according to the formula Mg.sub.3.2Sb.sub.1.3Bi.sub.0.5-xTe.sub.x that has an average ZT above 0.8 from 400K to 800K. The p-type and n-type materials discussed herein may be used alone, in combination with other materials, or in combination with each other in various configurations.

Systems and methods discussed herein relate to Zintl-type thermoelectric materials, including a p-type thermoelectric material according to the formula AM.sub.yX.sub.y, and includes at least one of calcium (Ca), europium (Eu), ytterbium (Yb), and strontium (Sr), and has a ZT of the above about 0.60 above 675K. The n-type thermoelectric component includes magnesium (Mg), tellurium (Te), antimony (Sb), and bismuth (Bi) according to the formula Mg.sub.3.2Sb.sub.1.3Bi.sub.0.5-xTe.sub.x that has an average ZT above 0.8 from 400K to 800K. The p-type and n-type materials discussed herein may be used alone, in combination with other materials, or in combination with each other in various configurations.

A titanium-free cobalt-chromium alloy for a powder, contains (in wt.%) C 0.40 -1.50%, Cr 24.0 - 32.0%, W 3.0 - 8.0%, Mo 0.1 - 5.0%, where 4.0 < W + Mo < 9.5 is satisfied by the content of W and Mo in wt.%, Nb max. 0.5%, Ta max. 0.5 %, where Nb + Ta < 0.8 is satisfied by the content of Nb and Ta in wt.%, Ni 0.005 - 25.0%, Fe 0.005 -15.0%, where Ni + Fe > 3.0 is satisfied by the content of Ni and Fe in wt.%, Mn 0.005 -5.0%, Al max. 0.5%, N 0.0005 - 0.15%, Si < 0.3%, Cu max. 0.4%, O 0.0001 - 0.1%, P max. 0.015%, B max. 0.015%, S max. 0.015%, residual Co, and impurities resulting from the production process, in particular Zr max. 0.03% and Ti max. 0.025%.

A titanium-free cobalt-chromium alloy for a powder, contains (in wt.%) C 0.40 -1.50%, Cr 24.0 - 32.0%, W 3.0 - 8.0%, Mo 0.1 - 5.0%, where 4.0 < W + Mo < 9.5 is satisfied by the content of W and Mo in wt.%, Nb max. 0.5%, Ta max. 0.5 %, where Nb + Ta < 0.8 is satisfied by the content of Nb and Ta in wt.%, Ni 0.005 - 25.0%, Fe 0.005 -15.0%, where Ni + Fe > 3.0 is satisfied by the content of Ni and Fe in wt.%, Mn 0.005 -5.0%, Al max. 0.5%, N 0.0005 - 0.15%, Si < 0.3%, Cu max. 0.4%, O 0.0001 - 0.1%, P max. 0.015%, B max. 0.015%, S max. 0.015%, residual Co, and impurities resulting from the production process, in particular Zr max. 0.03% and Ti max. 0.025%.