Columnar crystal permanent magnet and method of preparation
AssigneeKabushiki Kaisha Suwa Seikosha
InventorsItaru Okonogi, Tatsuya Shimoda
Life of this patent
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Abstract
A permanent magnet formed from a powdered alloy ingot of samarium (Sm) and cobalt (Co), copper (Cu), and iron (Fe) and at least one element selected from the group consisting of zirconium (Zr), titanium (Ti), hafnium (Hf), tantalum (Ta), niobium (Nb), and vanadium (V), formed predominantly of Sm.sub.2 Co.sub.17 crystals and having at least 50 volume percent columnar crystals in the macrostructure is provided. The alloy ingots having increased columnar crystals are prepared by melting the alloy composition at a temperature at least about 320.degree. C. above the melting point of the composition and casting the ingot at a casting speed faster than about 5.0 sec/kg of alloy.
Claims25
A permanent magnet alloy ingot comprising an alloy of samarium (Sm) and cobalt (Co), copper (Cu), iron (Fe) and at least one element (M) selected from the group of elements consisting of zirconium (Zr), titanium (Ti), hafnium (Ha), tantalum (Ta), niobium (Nb) and vanadium (V), formed predominately of Sm.sub.2 Co.sub.17 crystals and having at least about 50 volume percent columnar crystals in the macrostructure of the alloy.
A process of preparing a permanent magnet alloy ingot formed from an alloy composition of samarium (Sm) and cobalt (Co), copper (Cu), iron (Fe) and at least one element (M) selected from the group consisting of zirconium (Zr), titanium (Ti), hafnium (Hf), tantalum (Ta), niobium (Nb) and vanadium (V), including predominately Sm.sub.2 Co.sub.17 crystals and having at least 50 volume percent columnar crystals in macrostructure of the ingot comprising:
- melting the alloy composition at a temperature of at least about 320.degree. C. higher than the melting point of the alloy composition;
- and
- casting the ingot in a mold at a casting speed of at least about 5.0 sec/kg of alloy to obtain an alloy ingot.
A powder-bonded permanent magnet comprising a compressed magnetic powder of an alloy of samarium (Sm) and cobalt (Co), copper (Cu), iron (Fe) and at least one element (M) selected from the group of elements consisting of zirconium (Zr), titanium (Ti), hafnium (Hf), tantalum (Ta), niobium (Nb) and vanadium (V), formed predominately of Sm.sub.2 Co.sub.17 crystals formed from an alloy ingot having at least about 50 volume percent columnar crystals in the macrostructure, said ingot prepared by mixing the components to form an alloy composition, melting the composition at a temperature at least about 320.degree. C. higher than the melting point of the composition and casting to form an alloy ingot at a casting speed of at least about 5.0 sec/kg of alloy.
A process of preparing a powder-bonded permanent magnet from an alloy ingot of samarium (Sm) and cobalt (Co), copper (Cu), iron (Fe) and at least one element (M) selected from the group consisting of zirconium (Zr), titanium (Ti), hafnium (Hf), tantalum (Ta), niobium (Nb) and vanadium (V), including predominately Sm.sub.2 Co.sub.17 crystals having a substantially columnar macrostructure when cast, comprising:
- mixing in an inert atmosphere an alloy composition including Sm between about 21 and 28 weight percent, Cu between about 3 and 10 weight percent, Fe between about 14 and 35 weight percent, M between about 0.5 and 5.0 weight percent with the balance cobalt to make up 100 weight percent;
- melting the alloy composition at a temperature of at least about 320.degree. C. above the melting point of the composition;
- casting the composition at a casting speed of at least about 5.0 sec/kg to obtain an alloy ingot;
- subjecting the alloy ingot to a thermal treatment step;
- pulverizing the ingot to a powder;
- and
- compressing the magnetic powder in a magnetic field to form the permanent magnet.
A permanent magnet alloy ingot comprising an alloy of samarium (Sm) and cobalt (Co), copper (Cu), iron (Fe) and at least one element (M) selected from the group of elements consisting of zirconium (Zr), titanium (Ti), hafnium (Hf), tantalum (Ta), niobium (Nb) and vanadium (V) formed predominately of Sm.sub.2 Co.sub.17 crystals and having at least about 50 volume percent columnar crystals in the macro-structure of the alloy, formed by:
- melting the alloy composition at a temperature of at least about 320.degree. C. higher than the melting point of the alloy composition;
- and
- casting the alloy into an ingot in a mold at a casting speed of at least about 5.0 sec/kg of alloy to obtain the alloy ingot.
A powder-bonded permanent magnet formed from an alloy ingot of samarium (Sm) and cobalt (Co), copper (Cu), iron (Fe) and at least one element (M) selected from the group consisting of zirconium (Zr), titanium (Ti), hafnium (Hf), tantalum (Ta), niobium (Nb) and vanadium (V) including predominantly Sm.sub.2 Co.sub.17 crystals having a substantially columnar microstructure when cast, obtained by:
- mixing in an inert atmosphere an alloy composition including Sm between about 21 and 28 weight percent, Cu between about 3 and 10 weight percent, Fe between about 14 and 35 weight percent, M between about 0.5 and 5.0 weight percent with the balance cobalt to make up 100 weight percent;
- melting the alloy composition at a temperature of at least about 320.degree. C. above the melting point of the composition;
- casting the composition at a casting speed of at least about 5.0 sec/kg to obtain an alloy ingot;
- subjecting the alloy ingot to a thermal treatment step;
- pulverizing the ingot to a powder;
- and
- compressing the magnetic powder in a magnetic field to form the permanent magnet.
Dependencies are inferred from the claim text.