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.
A high magnetic permeability heat-treated alloy for recording and reproducing heads, consisting essentially of Element % by Weight
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Ni 75 - 82
Fe 5 - 24
Al 1 - 5
Mo 0 - 6
Cu 0 - 15
______________________________________ and at least one additive, said additive being Element % by Weight
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Nb 2 - 7
Si 0.4 - 2
Cr 1 - 5
______________________________________ , or a mixture thereof wherein said μ ri is at least 10,000 and said Hv is at least 160, said alloy having an initial relative magnetic permeability (μ ri ) expressed by line μ ri of FIG. 1 of the drawings and a Vicker's hardness (Hv) expressed by line Hv of FIG. 1 of the drawings as the aluminum content of the alloy increases from 1 to 5 percent.
Claim 2
Dependent Claim
136 words
A high magnetic permeability heat-treated alloy for recording and reproducing heads, consisting essentially of Element % by Weight
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Ni 75 - 82
Fe 5 - 24
Al 1 - 5
Mo 0 - 6
Cu 0 - 15
______________________________________ and at least one additive, said additive being Element % by Weight
______________________________________
Nb 2 - 7
Si 0.4 - 2
Cr 1 - 5
______________________________________ , or a mixture thereof wherein said μ ri is at least 10,000 and said Hv is at least 160, said alloy having an initial relative magnetic permeability (μ ri ) expressed by line μ ri of FIG. 1 of the drawings and a Vicker's hardness (Hv) expressed by line Hv of FIG. 1 of the drawings as the aluminum content of the alloy increases from 1 to 5 percent.
Claim 3
Dependent Claim
17 words
The alloy of claim 1, wherein said Cu is present in amounts ranging between 3-15% by weight.
Claim 4
Dependent Claim
10 words
The alloy of claim 1, wherein said additive is Cr.