Method for producing a rare earth metal-iron-boron permanent magnet by use of a rapidly-quenched alloy powder

Claim 1

A method for producing a transition metal-rare earth metal-boron permanent magnetic body with a high energy product and a reduced oxygen content, said permanent magnet body comprising a solid solution phase and magnetic crystalline particles dispersed within said solid solution phase, which comprises steps of: preparing an ingot of R--T--B magnetic alloy comprising a magnetic intermetallic compound represented by a chemical formula of R 2 T 14 B, where R is at least one element selected from the group consisting of yttrium (Y) and rare earth metals, T is at least one transition metal comprising 50-100 at % iron on the basis of the total transition metal; pulverizing and milling said ingot to thereby prepare a magnetic alloy powder; preparing a rapidly quenched alloy body by rapidly quenching a melt comprising at least one metal element (R) selected from the group consisting of yttrium (Y) and rare earth metals and at least one of boron (B) and a transition metal (T); pulverizing and milling said rapidly quenched alloy body to thereby produce a rapidly-quenched alloy powder; mixing said rapidly-quenched alloy powder with said magnetic alloy powder to provide a mixed powder containing said rapidly quenched alloy powder in an amount of 70% or less by volume; compacting said mixed powder into a compact body of a desired shape; and liquid sintering said compact body at an elevated liquid sintering temperature to produce the permanent magnetic body wherein said rapidly-quenched alloy powder melts to a liquidus phase which cements the magnetic alloy powder and a part of the liquidus phase substantially generates the magnetic crystalline particles and the remaining portion of the liquidus phase generates the solid solution phase upon cooling from the liquid sintering temperature.

Claim 2

A method for producing a transition metal-rare earth metal-boron permanent magnetic body with a high energy product and a reduced oxygen content, said permanent magnet body comprising a solid solution phase and magnetic crystalline particles dispersed within said solid solution phase, which comprises steps of: preparing an ingot of R--T--B magnetic alloy comprising a magnetic intermetallic compound represented by a chemical formula of R 2 T 14 B, where R is at least one element selected from the group consisting of yttrium (Y) and rare earth metals, T is at least one transition metal comprising 50-100 at % iron on the basis of the total transition metal; pulverizing and milling said ingot to thereby prepare a magnetic alloy powder; preparing a rapidly quenched alloy body by rapidly quenching a melt comprising at least one metal element (R) selected from the group consisting of yttrium (Y) and rare earth metals and at least one of boron (B) and a transition metal (T); pulverizing and milling said rapidly quenched alloy body to thereby produce a rapidly-quenched alloy powder; mixing said rapidly-quenched alloy powder with said magnetic alloy powder to provide a mixed powder containing said rapidly quenched alloy powder in an amount of 70% or less by volume; compacting said mixed powder into a compact body of a desired shape; and liquid sintering said compact body at an elevated liquid sintering temperature to produce the permanent magnetic body wherein said rapidly-quenched alloy powder melts to a liquidus phase which cements the magnetic alloy powder and a part of the liquidus phase substantially generates the magnetic crystalline particles and the remaining portion of the liquidus phase generates the solid solution phase upon cooling from the liquid sintering temperature.