A method for manufacturing FeNi ordered alloy having a L1.sub.0 type order structure is provided. After a nitrification process for nitriding a powder sample of a FeNi disordered alloy arranged in a tube furnace is performed using a NH.sub.3 gas, a de-nitrification process for removing a nitrogen from the FeNi disordered alloy which is processed by the nitrification process is performed using a H.sub.2 gas. Thus, the L1.sub.0 type FeNi ordered alloy with a regularity defined by S equal to or higher than 0.5 is obtained.

A method for manufacturing FeNi ordered alloy having a L1.sub.0 type order structure is provided. After a nitrification process for nitriding a powder sample of a FeNi disordered alloy arranged in a tube furnace is performed using a NH.sub.3 gas, a de-nitrification process for removing a nitrogen from the FeNi disordered alloy which is processed by the nitrification process is performed using a H.sub.2 gas. Thus, the L1.sub.0 type FeNi ordered alloy with a regularity defined by S equal to or higher than 0.5 is obtained.

The invention relates to a fuel tank (1), in particular a hydrogen tank, for a fuel cell system, having a monolithic base body (10) made of a metal alloy, wherein the base body (10) has a first inner layer (11) having a first inner structure and a second outer layer (12) having a second inner structure, which differs from the first inner structure, and wherein the first inner structure is formed from a metastable austenite and the second inner structure is formed from a martensite.

A method for manufacturing FeNi ordered alloy having a L1.sub.0 type order structure is provided. After a nitrification process for nitriding a powder sample of a FeNi disordered alloy arranged in a tube furnace is performed using a NH.sub.3 gas, a de-nitrification process for removing a nitrogen from the FeNi disordered alloy which is processed by the nitrification process is performed using a H.sub.2 gas. Thus, the L1.sub.0 type FeNi ordered alloy with a regularity defined by S equal to or higher than 0.5 is obtained.

A method for manufacturing FeNi ordered alloy having a L1.sub.0 type order structure is provided. After a nitrification process for nitriding a powder sample of a FeNi disordered alloy arranged in a tube furnace is performed using a NH.sub.3 gas, a de-nitrification process for removing a nitrogen from the FeNi disordered alloy which is processed by the nitrification process is performed using a H.sub.2 gas. Thus, the L1.sub.0 type FeNi ordered alloy with a regularity defined by S equal to or higher than 0.5 is obtained.

The present invention discloses a gold-colored steel sheet capable of expressing color without peeling of a modified layer and the gold-colored steel sheet capable of forming a color-modified layer through a conventional annealing process without expensive facilities.

A method of manufacturing the gold-colored steel sheet according to an embodiment of the present invention can form a TiN modified layer on a surface of a steel sheet comprising 0.3 to 1.5 wt % of titanium (Ti) by an annealing treatment in a nitrogen (N.sub.2) atmosphere at 900 to 1,200 C. for 30 to 300 seconds.

An FeNi ordered alloy has an L1.sub.0 ordered structure, a mean order degree of 0.4 or more throughout a material, and a coercivity of 87.5 kA/m or more. For example, a nitriding treatment of an FeNi random alloy is performed and then a nitriding treatment is performed to obtain an L1.sub.0-FeNi ordered alloy. A volume mean particle size of a FeNi random alloy is, for example, 45 nm or more, and a treatment temperature of the nitriding treatment is, for example, greater than or equal to 300 degrees Celsius and is less than or equal to 500 degrees Celsius, and a treatment period is, for example, 10 hours or longer.

An FeNi ordered alloy has an L1.sub.0 ordered structure, a mean order degree of 0.4 or more throughout a material, and a coercivity of 87.5 kA/m or more. For example, a nitriding treatment of an FeNi random alloy is performed and then a nitriding treatment is performed to obtain an L1.sub.0-FeNi ordered alloy. A volume mean particle size of a FeNi random alloy is, for example, 45 nm or more, and a treatment temperature of the nitriding treatment is, for example, greater than or equal to 300 degrees Celsius and is less than or equal to 500 degrees Celsius, and a treatment period is, for example, 10 hours or longer.

Methods for forming a dual-phase magnetic component from an initial component comprising a non-magnetic austenite composition are provided. The method may include: forming a coating on a portion of the surface of the initial component to form a masked area while leaving an unmasked area thereon. Thereafter the initial component may be heated to a treatment temperature such that nitrogen diffuses out of the unmasked area of the initial component to transform the non-magnetic austenite composition to a magnetic phase in the unmasked area. Thereafter, the initial component may be cooled from the treatment temperature to form a dual-phase magnetic component having a magnetic region corresponding to the unmasked area and a non-magnetic region corresponding to the masked area.

Methods for forming a dual-phase magnetic component from an initial component comprising a non-magnetic austenite composition are provided. The method may include: forming a coating on a portion of the surface of the initial component to form a masked area while leaving an unmasked area thereon. Thereafter the initial component may be heated to a treatment temperature such that nitrogen diffuses out of the unmasked area of the initial component to transform the non-magnetic austenite composition to a magnetic phase in the unmasked area. Thereafter, the initial component may be cooled from the treatment temperature to form a dual-phase magnetic component having a magnetic region corresponding to the unmasked area and a non-magnetic region corresponding to the masked area.