A sputtering target according to the present invention contains Co and Pt as metal components, wherein a molar ratio of a content of Pt to a content of Co is from 5/100 to 45/100, and wherein the sputtering target contains Nb.sub.2O.sub.5 as a metal oxide component.

Provided are a magnetic tape including a non-magnetic support and a magnetic layer including a ferromagnetic powder, a magnetic tape cartridge and a magnetic tape apparatus including this magnetic tape. An amount of a fluid lubricant collected by wiping a surface of the magnetic layer by a nonwoven fabric is in a range of 5 to 400 ng/m.sup.2 as a value per unit area of the surface of the magnetic layer.

A sputtering target according to the present invention contains Co and Pt as metal components, wherein a molar ratio of a content of Pt to a content of Co is from 5/100 to 45/100, and wherein the sputtering target contains Nb.sub.2O.sub.5 as a metal oxide component.

The present invention provides a substrate for a magnetic recording medium in which bulges are hardly formed on a surface thereof by a physical impact in a size for a 3.5-inch type HDD, and a width of displacement caused by fluttering is small. The substrate for a magnetic recording medium includes an Al alloy substrate and a Ni alloy plating film formed on a surface of the Al alloy substrate, and has a diameter of 95 to 98 mm, a disk shape having a hole whose inner diameter ranges from 19 to 26 mm in the center thereof, a thickness of 0.48 to 0.64 mm, and a mass of 9.0 to 15.0 g. The Al alloy substrate has a Young's modulus (E) of 74 GPa or more, a density () of 2.75 g/cm.sup.3 or less, and a ratio (E/) of 27 or more between the Young's modulus (E) and the density (). The Ni alloy plating film has a thickness of 4 to 7 m, and when an indentation is formed by pressing a diamond indentor whose tip has a square pyramid shape against a surfaces of the Ni alloy plating film with a test force of 0.49 N for 10 seconds in a vertical direction, an average height of bulges generated around the indentation ranges from 10 to 50 nm.

What is provided is an aluminum alloy substrate for a magnetic recording medium which has high rigidity and an excellent plating properties. The aluminum alloy substrate for a magnetic recording medium has a constitution in which coarse grains whose average grain size is within a range that exceeds 2 m and is less than or equal to 20 m are dispersed, the average number of coarse grains per area of 0.042 mm.sup.2 is 100 or more, and a surface roughness Ra is less than or equal to 0.2 m.

The present invention provides a substrate for a magnetic recording medium in which bulges are not easily formed on a surface thereof by a physical impact in a size for a 2.5-inch type hard disk drive, and a width of displacement caused by fluttering is small. The substrate for a magnetic recording medium includes an Al alloy substrate and a Ni alloy plating film formed on a surface of the Al alloy substrate, has a diameter of 54 to 70 mm, and a disk shape having a hole whose inner diameter ranges from 19 to 26 mm in the center thereof. The Al alloy substrate has a Young's modulus (E) of 74 GPa or more, a density () of 2.75 g/cm.sup.3 or less, and a ratio (E/) of 27 or more between the Young's modulus (E) and the density (). The Ni alloy plating film has a thickness of 4 to 7 m, and when an indentation is formed by pressing a diamond indentor whose tip has a square pyramid shape against a surface of the Ni alloy plating film with a test force of 0.49 N for 10 seconds in a vertical direction, an average height of bulges generated around the indentation ranges from 10 to 50 nm.

A sputtering target according to the present invention contains Co and Pt as metal components, wherein a molar ratio of a content of Pt to a content of Co is from 5/100 to 45/100, and wherein the sputtering target contains Nb.sub.2O.sub.5 as a metal oxide component.

Provided are a magnetic tape including a non-magnetic support and a magnetic layer including a ferromagnetic powder, a magnetic tape cartridge and a magnetic tape apparatus including this magnetic tape. An amount of a fluid lubricant collected by wiping a surface of the magnetic layer by a nonwoven fabric is in a range of 5 to 400 ng/m.sup.2 as a value per unit area of the surface of the magnetic layer.