Ternary chromium-molybdenum-aluminum (CrMoAl) alloys that form oxidation-resistant surface films for high-temperature applications are provided. Also provided are methods for thermally pre-treating the alloys to form the oxidation resistant surface films. The surface films have a stratified structure that includes an exterior surface oxide layer comprising chromium oxides and aluminum oxides and an interior aluminum nitride-rich region comprising aluminum nitride precipitates dispersed in a CrMoAl alloy matrix. The interior aluminum nitride precipitates act as oxygen sinks to sequester oxygen diffusing inward into the CrMoAl to prevent further oxidation of the underlying bulk alloy.

Ternary chromium-molybdenum-aluminum (CrMoAl) alloys that form oxidation-resistant surface films for high-temperature applications are provided. Also provided are methods for thermally pre-treating the alloys to form the oxidation resistant surface films. The surface films have a stratified structure that includes an exterior surface oxide layer comprising chromium oxides and aluminum oxides and an interior aluminum nitride-rich region comprising aluminum nitride precipitates dispersed in a CrMoAl alloy matrix. The interior aluminum nitride precipitates act as oxygen sinks to sequester oxygen diffusing inward into the CrMoAl to prevent further oxidation of the underlying bulk alloy.

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.

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.

An object of the present invention is to provide, at a low cost, a porous metal body that can be used in an electrode of a fuel cell and that has better corrosion resistance. The porous metal body has a three-dimensional mesh-like structure and contains nickel (Ni), tin (Sn), and chromium (Cr). A content ratio of the tin is 10% by mass or more and 25% by mass or less, and a content ratio of the chromium is 1% by mass or more and 10% by mass or less. On a cross section of a skeleton of the porous metal body, the porous metal body contains a solid solution phase of chromium, nickel, and tin. The solid solution phase contains a solid solution phase of chromium and trinickel tin (Ni.sub.3Sn), the solid solution phase having a chromium content ratio of 2% by mass or less, and does not contain a solid solution phase that is other than a solid solution phase of chromium and trinickel tin (Ni.sub.3Sn) and that has a chromium content ratio of less than 1.5% by mass.

An object of the present invention is to provide, at a low cost, a porous metal body that can be used in an electrode of a fuel cell and that has better corrosion resistance. The porous metal body has a three-dimensional mesh-like structure and contains nickel (Ni), tin (Sn), and chromium (Cr). A content ratio of the tin is 10% by mass or more and 25% by mass or less, and a content ratio of the chromium is 1% by mass or more and 10% by mass or less. On a cross section of a skeleton of the porous metal body, the porous metal body contains a solid solution phase of chromium, nickel, and tin. The solid solution phase contains a solid solution phase of chromium and trinickel tin (Ni.sub.3Sn), the solid solution phase having a chromium content ratio of 2% by mass or less, and does not contain a solid solution phase that is other than a solid solution phase of chromium and trinickel tin (Ni.sub.3Sn) and that has a chromium content ratio of less than 1.5% by mass.

Austenitic stainless alloys have been discovered that exhibit unexpectedly superior corrosion resistance, particularly to sulfuric acid solutions, when compared to that exhibited by conventional alloys with closely related compositions. These alloys advantageously are corrosion resistant to a relatively wide range of sulfuric acid concentration and temperature and are thus particularly suitable for use in the industrial production of sulfuric acid.

A metal material includes a metal having a body-centered cubic structure, in which with respect to a sum of orientation area fractions of a {001} plane, a {101} plane and a {111} plane, a ratio of the orientation area fraction of the {111} plane is 0.45 or more.

Ternary chromium-molybdenum-aluminum (CrMoAl) alloys that form oxidation-resistant surface films for high-temperature applications are provided. Also provided are methods for thermally pre-treating the alloys to form the oxidation resistant surface films. The surface films have a stratified structure that includes an exterior surface oxide layer comprising chromium oxides and aluminum oxides and an interior aluminum nitride-rich region comprising aluminum nitride precipitates dispersed in a CrMoAl alloy matrix. The interior aluminum nitride precipitates act as oxygen sinks to sequester oxygen diffusing inward into the CrMoAl to prevent further oxidation of the underlying bulk alloy.