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.

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.

A finish heat treatment apparatus for an iron powder. Raw iron powder is placed on a continuous moving hearth and continuously charged into the apparatus. In a pretreatment zone, the raw iron powder is subjected to a pretreatment of heating the raw iron powder in an atmosphere of hydrogen gas and/or inert gas at 450 to 1100° C. In decarburization, deoxidation, and denitrification zones, the pretreated iron powder is subsequently subjected to at least two treatments of decarburization, deoxidation, and denitrification. In the pretreatment zone, a hydrogen gas and/or an inert gas serving as a pretreatment ambient gas is introduced separately from an ambient gas used in the at least two treatments is introduced from the upstream side of the pretreatment zone and released from the downstream side so as to flow in the same direction as a moving direction of the moving hearth.

A finish heat treatment apparatus for an iron powder. Raw iron powder is placed on a continuous moving hearth and continuously charged into the apparatus. In a pretreatment zone, the raw iron powder is subjected to a pretreatment of heating the raw iron powder in an atmosphere of hydrogen gas and/or inert gas at 450 to 1100° C. In decarburization, deoxidation, and denitrification zones, the pretreated iron powder is subsequently subjected to at least two treatments of decarburization, deoxidation, and denitrification. In the pretreatment zone, a hydrogen gas and/or an inert gas serving as a pretreatment ambient gas is introduced separately from an ambient gas used in the at least two treatments is introduced from the upstream side of the pretreatment zone and released from the downstream side so as to flow in the same direction as a moving direction of the moving hearth.

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.

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.

A method for refining magnetic domains of a grain-oriented electrical steel sheet according to an exemplary embodiment of the present invention includes: a step of preparing a grain-oriented electrical steel sheet; and a step of forming a groove by irradiating a quasi-continuous laser beam of which a duty is from 98.0 to 99.9% on a surface of the grain-oriented electrical steel sheet.