An aluminum alloy disc blank for a magnetic disc made of an aluminum alloy containing Fe: 0.005 to 1.800 mass % with the balance being Al and inevitable impurities, wherein a flatness change of the aluminum alloy disc blank for a magnetic disc when the aluminum alloy disc blank for a magnetic disc is held in the atmosphere at 50? C. or lower for 336 hours is 2.0 ?m or less.

An aqueous electroless nickel-phosphorous plating bath for forming an electroless nickel-phosphorous coating on an alkaline zincate coated substrate includes about 1.0 g/l to less than 5.0 g/l Ni, about 25 g/l to about 40 g/l hypophosphorous reducing agent; and 0 to about 120 g/l orthophosphite by-product. The electroless nickel-phosphorous bath with an orthophosphite concentration of up to about 120 g/l provides an electroless nickel-phosphorous deposit on the zincate coated substrate with an intrinsic stress that is more compressive than electroless nickel-phosphorous deposit provided using conventional electroless nickel-phosphorous baths.

The present invention provides: an aluminum alloy substrate for magnetic discs with excellent plating surface smoothness; a manufacturing method therefor; and a magnetic disc using said aluminum alloy substrate for magnetic discs. The present invention is an aluminum alloy substrate for magnetic discs, a manufacturing method therefor, and a magnetic disc using said aluminum alloy substrate for magnetic discs, the aluminum alloy substrate being characterized in being obtained from an aluminum alloy containing Mg: 2.0-8.0 mass % (% below), Be: 0.00001-0.00200%, Cu: 0.003-0.150%, Zn: 0.05-0.60%, Cr: 0.010-0.300%, Si: 0.060% or less, Fe: 0.060% or less, the balance being obtained from Al and unavoidable impurities.

A base for a magnetic recording medium, includes a substrate made of an Al alloy and having a surface, and a film made of a NiWP-based alloy and plated on the surface of the substrate. The film includes W in a range of 15 mass % to 22 mass %, P in a range of 3 mass % to 10 mass %, and Pb in a range of 0.03 mass % to 0.08 mass %. The film has a thickness of 5 m or greater.

A base for a magnetic recording medium, includes a substrate made of an Al alloy and having a surface, and a film made of a NiWP-based alloy and plated on the surface of the substrate. The film includes W in a range of 15 mass % to 22 mass %, P in a range of 3 mass % to 10 mass %, and Pb in a range of 0.03 mass % to 0.08 mass %. The film has a thickness of 5 m or greater.

Systems and methods for controlling stray fields of a magnetic feature are provided. One such method can involve selecting a plurality of materials for a magnetic feature, selecting a plurality of additives, combining the plurality of materials for the magnetic feature and the plurality of additives in an electrolyte solution to form a combined solution, adding nitrogen to the combined solution, degassing the combined solution, depositing the combined solution as a thin film on a wafer using pulse plating, and lapping the thin film to form an edge of the magnetic feature. In several embodiments, the magnetic feature is a component of a magnetic transducer such as a writer pole, a reader shield, or a writer shield.

Systems and methods for controlling stray fields of a magnetic feature are provided. One such method can involve selecting a plurality of materials for a magnetic feature, selecting a plurality of additives, combining the plurality of materials for the magnetic feature and the plurality of additives in an electrolyte solution to form a combined solution, adding nitrogen to the combined solution, degassing the combined solution, depositing the combined solution as a thin film on a wafer using pulse plating, and lapping the thin film to form an edge of the magnetic feature. In several embodiments, the magnetic feature is a component of a magnetic transducer such as a writer pole, a reader shield, or a writer shield.