Abstract: In a metal-insulator alternate type multilayer head core usable for magnetic sound recording and reproducing, metallic component layers are connected to each other via one or more metallic interconnecting layers passing locally through insulating component layers in order to provide high effective permeability with minimized eddy current loss. In manufacturing, a metal-insulator alternate type multilayer construction including the metallic interconnecting layer or layers is subjected to sintering in order to avoid intermetal separation which might be otherwise caused by cracking in the insulating layers.

Abstract: In a metal-insulator alternate type multilayer head core usable for magnetic sound recording and reproducing, metallic component layers are connected to each other via one or more metallic interconnecting layers passing locally through insulating component layers in order to provide high effective permeability with minimized eddy current loss. In manufacturing, a metal-insulator alternate type multilayer construction including the metallic interconnecting layer or layers is subjected to sintering in order to avoid intermetal separation to be otherwise caused by cracking in the insulating layers.

Abstract: A material having a high magnetic permeability made by a basic composition consisting of 75-82 weight percent of nickel, 2-6 weight percent of molybdenum, 1 or less weight percent of manganese, 1 or less weight percent of silicon and the remainder iron, and by an additive consisting of at least two different types of elements, one of which types of elements being an element selected from a first group of elements consisting of zirconium, vanadium, tantalum, chromium and tungsten, and the other being at least one element selected from a second group of elements consisting of titanium, zirconium, vanadium, niobium, tantalum, chromium and tungsten but different from said an element of the first group, said additive being contained in said material in an amount within the range of 1-8 weight percent. This material exhibits a high mechanical strength, and a high resistance to wear due to friction and a high magnetic permeability.

Abstract: A material having a high magnetic permeability made by a base composition consisting essentially of, by weight, 75-82 percent of nickel and 5-24 percent of iron, with or without 2-6 percent of molybdenum, 1 or less percent of manganese, 1 or less percent of silicon, and by an additive mixture consisting of at least two different types of elements, one of which types of elements being at least one element selected from the group of elements consisting of titanium, zirconium, vanadium, niobium, chromium and tungsten, and the other being aluminum, said additive being contained in said base composition in an amount that the total content of said at least two different types of elements falls within the range of 1-8 percent of the whole weight of said material. This material exhibits a high mechanical strength, and toughness, a high resistance to wear from friction and a high magnetic permeability.

Abstract: By the inclusion, by weight, of 1-5% of aluminium, as the essential additive, in a 78 permalloy (an Fe-Ni alloy) having a basic composition comprising the two essential elements, i.e. 75-82% of nickel and 5-24% of iron, the hardness of this alloy is improved without deteriorating the magnetic characteristic including magnetic permeability of the alloy. Furthermore, molybdenum, copper, chromium, and niobium may be added together with the aluminum in a suitable combination and amount to enhance both the hardness and characteristic of the alloy, facilitating the heat treatment during the manufacture of the material of this invention. This improved material or alloy is obtained in a relatively simple procedure and is of a good workability and is suitable for use as the material of head cores of magnetic recording apparatuses.