Processes for producing low-nitrogen metallic chromium or chromium-containing alloys, which prevent the nitrogen in the surrounding atmosphere from being carried into the melt and being absorbed by the metallic chromium or chromium-containing alloy during the metallothermic reaction, include vacuum-degassing a thermite mixture comprising metal compounds and metallic reducing powders contained within a vacuum vessel, igniting the thermite mixture to effect reduction of the metal compounds within the vessel under reduced pressure i.e., below 1 bar, and conducting the entire reduction reaction in said vessel under reduced pressure, including solidification and cooling, to produce a final product with a nitrogen content below 10 ppm. The final products obtained, in addition to low-nitrogen metallic chromium in combination with other elements, can be used as raw materials in the manufacture of superalloys, stainless steel and other specialty steels whose final content of nitrogen is below 10 ppm.

A process for producing high-purity magnesium by distillation at reduced pressure, which includes providing an apparatus having a retort formed from a material inert with respect to magnesium and an upper region defined by two vertically spaced level lines, a condensation vessel having a lower region and an upper region extending into the upper region of the retort, wherein the retort and condensation vessel are coupled to one another by an opening arranged in the upper region of the condensation vessel; providing a magnesium-containing metal melt to the retort at a level below the gap; and heating and maintaining the upper region of the retort at a temperature above the boiling point of magnesium to fill the retort with steam, thereby delivering a high purity melt into the condensation vessel via the opening.

A process for producing high-purity magnesium by distillation at reduced pressure, which includes providing an apparatus having a retort formed from a material inert with respect to magnesium and an upper region defined by two vertically spaced level lines, a condensation vessel having a lower region and an upper region extending into the upper region of the retort, wherein the retort and condensation vessel are coupled to one another by an opening arranged in the upper region of the condensation vessel; providing a magnesium-containing metal melt to the retort at a level below the gap; and heating and maintaining the upper region of the retort at a temperature above the boiling point of magnesium to fill the retort with steam, thereby delivering a high purity melt into the condensation vessel via the opening.

A sublimation/distillation apparatus including a crucible with an open end, a heating device thermally coupled to the crucible, an actively cooled collection substrate disposed above the open end of the crucible, and a vacuum chamber housing the crucible, the heating device, and the actively cooled collection substrate.

A sublimation/distillation apparatus including a crucible with an open end, a heating device thermally coupled to the crucible, an actively cooled collection substrate disposed above the open end of the crucible, and a vacuum chamber housing the crucible, the heating device, and the actively cooled collection substrate.

A method of fabricating a low alloy steel ingot, the method including a) melting all or part of an electrode by a vacuum arc remelting method, the electrode, before melting, including iron and carbon, the melted portion of the electrode being collected in a crucible, thus forming a melt pool within the crucible; and b) solidifying the melt pool by heat exchange between the melt pool and a cooling fluid, the heat exchange applied serving to impose a mean solidification speed during step b) that is less than or equal to 45 m/s and to obtain an ingot of low alloy steel.

A method of fabricating a low alloy steel ingot, the method including a) melting all or part of an electrode by a vacuum arc remelting method, the electrode, before melting, including iron and carbon, the melted portion of the electrode being collected in a crucible, thus forming a melt pool within the crucible; and b) solidifying the melt pool by heat exchange between the melt pool and a cooling fluid, the heat exchange applied serving to impose a mean solidification speed during step b) that is less than or equal to 45 m/s and to obtain an ingot of low alloy steel.

Processes for producing low nitrogen, essentially nitride-free chromium or chromium plus niobium-containing nickel-based alloys include charging elements or compounds which do not dissolve appreciable amounts of nitrogen in the molten state to a refractory crucible within a vacuum induction furnace, melting said elements or compounds therein under reduced pressure, and effecting heterogeneous carbon-based bubble nucleation in a controlled manner. The processes also include, upon cessation of bubble formation, adding low nitrogen chromium or a low nitrogen chromium-containing master alloy with a nitrogen content of below 10 ppm to the melt, melting and distributing said added chromium or chromium-containing master alloy throughout the melt, bringing the resulting combined melt to a temperature and surrounding pressure to permit tapping, and tapping the resulting melt, directly or indirectly, to a metallic mold and allowing the melt to solidify and cool under reduced pressure.

Processes for producing low nitrogen, essentially nitride-free chromium or chromium plus niobium-containing nickel-based alloys include charging elements or compounds which do not dissolve appreciable amounts of nitrogen in the molten state to a refractory crucible within a vacuum induction furnace, melting said elements or compounds therein under reduced pressure, and effecting heterogeneous carbon-based bubble nucleation in a controlled manner. The processes also include, upon cessation of bubble formation, adding low nitrogen chromium or a low nitrogen chromium-containing master alloy with a nitrogen content of below 10 ppm to the melt, melting and distributing said added chromium or chromium-containing master alloy throughout the melt, bringing the resulting combined melt to a temperature and surrounding pressure to permit tapping, and tapping the resulting melt, directly or indirectly, to a metallic mold and allowing the melt to solidify and cool under reduced pressure.

A method of purifying yttrium involves purifying element yttrium by high-temperature saturated dissolution, low-temperature recrystallization, high-temperature reduction and vaporization-based removal of impurities, in a simple manner, and at a low cost, such that yttrium element is unlikely to be contaminated by any raw material used in a manufacturing process.