The invention relates to a nuclear reactor operating according to the dual fluid principle with a special liquid metal fissionable mixture as liquid fuel in the liquid fuel line, which has a high percentage of actinoids, preferably 69% and higher. Preferred metals are selected from chromium (Cr), manganese (Mn) and iron (Fe). Preferred actinoids are selected from thorium (Th), uranium (U) and plutonium (Pu). The mixtures and resulting multicomponent alloys need not necessarily be an eutectic.

In a method for manufacturing a solder joint part, at least one of a first metal base material and a second metal base material is an alloy containing Ni in an amount of more than 0 wt % and less than 44 wt % and Cu in an amount of more than 56 wt %, and solder is a solder alloy containing Ga and inevitable impurities or a solder alloy containing Ga as a main component and having a melting point of 30° C. or lower. The method includes applying the solder to a surface of the first metal base material and placing the second metal base material on the applied solder, and heating the first and second metal base materials to a temperature of 90° C. or lower in a specified atmosphere or in a liquid to generate CuGa.sub.2 or (Cu, Ni)Ga.sub.2 between the first and second metal base materials, thereby joining the first and second metal material.

In a method for manufacturing a solder joint part, at least one of a first metal base material and a second metal base material is an alloy containing Ni in an amount of more than 0 wt % and less than 44 wt % and Cu in an amount of more than 56 wt %, and solder is a solder alloy containing Ga and inevitable impurities or a solder alloy containing Ga as a main component and having a melting point of 30° C. or lower. The method includes applying the solder to a surface of the first metal base material and placing the second metal base material on the applied solder, and heating the first and second metal base materials to a temperature of 90° C. or lower in a specified atmosphere or in a liquid to generate CuGa.sub.2 or (Cu, Ni)Ga.sub.2 between the first and second metal base materials, thereby joining the first and second metal material.

A sintered R-T-B based magnet work contains R: 27.5 to 35.0 mass % (R is at least one rare-earth element which always includes Nd), B: 0.80 to 0.99 mass %, Ga: 0 to 0.8 mass %, M: 0 to 2 mass % (M is at least one of Cu, Al, Nb and Zr), and a balance T (T is at least one transition metal element which always includes Fe, with 10% or less of Fe replaceable by Co). [T]/55.85>14[B]/10.8 is satisfied where [T] is the T content (mass %) and [B] is the B content (mass %). At least a portion of a Pr—Ga alloy is in contact with a portion of the sintered magnet work surface, and a first heat treatment is performed at a temperature between 600° C. and 950° C. A second heat treatment is performed at a temperature lower than the temperature of the first heat treatment and between 450° C. and 750° C.

A sintered R-T-B based magnet work contains R: 27.5 to 35.0 mass % (R is at least one rare-earth element which always includes Nd), B: 0.80 to 0.99 mass %, Ga: 0 to 0.8 mass %, M: 0 to 2 mass % (M is at least one of Cu, Al, Nb and Zr), and a balance T (T is at least one transition metal element which always includes Fe, with 10% or less of Fe replaceable by Co). [T]/55.85>14[B]/10.8 is satisfied where [T] is the T content (mass %) and [B] is the B content (mass %). At least a portion of a Pr—Ga alloy is in contact with a portion of the sintered magnet work surface, and a first heat treatment is performed at a temperature between 600° C. and 950° C. A second heat treatment is performed at a temperature lower than the temperature of the first heat treatment and between 450° C. and 750° C.

A sintered R-T-B based magnet includes a main phase crystal grain and a grain boundary phase, in which R: not less than 27.5 mass % and not more than 35.0 mass % (R always includes at least Nd and Pr); B: not less than 0.80 mass % and not more than 1.05 mass %; Ga: not less than 0.05 mass % and not more than 1.0 mass %; M: not more than 2 mass % (where M is at least one of Cu, Al, Nb, and Zr); and a balance T (where T is Fe, or Fe and Co) and impurities. At 300-μm depth from the magnet surface, a Pr/Nd ratio in a central portion of a main phase crystal grain is lower than 1, and a Pr/Nd ratio in an intergranular grain boundary is higher than 1. The Ga concentration gradually decreases in a portion of the magnet from the surface toward the interior.

A sintered R-T-B based magnet includes a main phase crystal grain and a grain boundary phase, in which R: not less than 27.5 mass % and not more than 35.0 mass % (R always includes at least Nd and Pr); B: not less than 0.80 mass % and not more than 1.05 mass %; Ga: not less than 0.05 mass % and not more than 1.0 mass %; M: not more than 2 mass % (where M is at least one of Cu, Al, Nb, and Zr); and a balance T (where T is Fe, or Fe and Co) and impurities. At 300-μm depth from the magnet surface, a Pr/Nd ratio in a central portion of a main phase crystal grain is lower than 1, and a Pr/Nd ratio in an intergranular grain boundary is higher than 1. The Ga concentration gradually decreases in a portion of the magnet from the surface toward the interior.

An electrochemically active material includes a silicon alloy material having the formula:
Si.sub.wM.sup.1.sub.xC.sub.yO.sub.z,
where w, x, y, and z represent atomic % values and w+x+y+z=1; M.sup.1 comprises a transition metal; w>0; x>0; y≥0; and z≥0. The electrochemically active material also includes a metal-based material having the formula:
M.sup.2.sub.aO.sub.bA.sub.c,
where a, b, and c represent atomic % values and a+b+c=1; M.sup.2 comprises a metal; A is an anion; a>0; b≥0; and c≥0.

An electrochemically active material includes a silicon alloy material having the formula:
Si.sub.wM.sup.1.sub.xC.sub.yO.sub.z,
where w, x, y, and z represent atomic % values and w+x+y+z=1; M.sup.1 comprises a transition metal; w>0; x>0; y≥0; and z≥0. The electrochemically active material also includes a metal-based material having the formula:
M.sup.2.sub.aO.sub.bA.sub.c,
where a, b, and c represent atomic % values and a+b+c=1; M.sup.2 comprises a metal; A is an anion; a>0; b≥0; and c≥0.

Undercooled liquid metallic core-shell particles, whose core is stable against solidification at ambient conditions, i.e. under near ambient temperature and pressure conditions, are used to join or repair metallic non-particulate components. The undercooled-shell particles in the form of nano-size or micro-size particles comprise an undercooled stable liquid metallic core encapsulated inside an outer shell, which can comprise an oxide or other stabilizer shell typically formed in-situ on the undercooled liquid metallic core. The shell is ruptured to release the liquid phase core material to join or repair a component(s).