Nd-Fe-B rare earth permanent magnet material

Abstract

A rare earth permanent magnet material is based on an R-Fe-Co-B-Al-Cu system wherein R is at least one element selected from Nd, Pr, Dy, Tb, and Ho, 15 to 33% by weight of Nd being contained. At least two compounds selected from M-B, M-B-Cu and M-C compounds (wherein M is Ti, Zr or Hf) and an R oxide have precipitated within the alloy structure as grains having an average grain size of up to 5 mum which are uniformly distributed in the alloy structure at intervals of up to 50 mum.

Description

technical field

[0001] The invention relates to a Nd-Fe-B based rare earth permanent magnet material. Background technique

[0002] Rare earth permanent magnets are commonly used in electrical and electronic devices due to their excellent magnetic properties and economy. Recently, demands for improving their performance continue to increase.

[0003] In order to improve the magnetic properties of R-Fe-B based rare earth permanent magnets, it is necessary to increase the R that exists as the main phase component in the alloy 2 Fe 14 B 1 phase ratio. This means reducing the Nd-rich phase which is a non-magnetic phase. This in turn requires reducing the concentration of oxygen, carbon and nitrogen in the alloy to minimize oxidation, carburization and nitriding of the Nd-rich phase.

[0004] However, reducing the oxygen concentration in the alloy creates the possibility of anomalous grain growth during sintering, resulting in high remanence Br, but...

Examples

Embodiment 1

[0047] Starting materials: neodymium, praseodymium, electrolytic iron, cobalt, iron-boron alloys, aluminum, copper and titanium formulated as 28.9Nd-2.5Pr-balance Fe-4.5Co-1.2B-0.7Al-0.4Cu by weight - a composition of xTi (where x = 0, 0.04, 0.4 or 1.4), followed by the preparation of the corresponding alloys by a single roll quenching process. Then put these alloys at +1.5±0.3kgf / cm 2 Hydrogenation in a hydrogen atmosphere, at a maximum of 10 -2 Dehydrogenation was carried out at 800° C. for 3 hours under Torr vacuum. Each alloy after hydrogenation and dehydrogenation is in the form of a coarse powder with a particle size of several hundreds of micrometers. Each of the coarse powders was mixed with 0.1 wt % stearic acid as a lubricant in a V-blender, and pulverized in a jet mill under nitrogen flow to an average particle size of about 3 μm. The resulting fine powder was filled into a die, oriented in a magnetic field of 25 kOe, and 0.5 metric tons / cm 2 compacted under pre...

Embodiment 2

[0053] Starting materials: relatively high carbon concentrations of neodymium, dysprosium, electrolytic iron, cobalt, iron-boron alloys, aluminum, copper and titanium formulated to be 28.6Nd-2.5Dy-balance by weight Fe-9.0Co-1.0B- The composition of 0.8Al-0.6Cu-xTi (where x=0.01, 0.2, 0.6 or 1.5) was used to compare the effects of different titanium additions, and then an ingot of the corresponding composition was prepared by high-frequency melting and casting into a water-cooled copper mold. The ingots were crushed in a Brown mill. Each coarse powder thus obtained was mixed with 0.05% by weight of lauric acid as a lubricant in a V-blender, and pulverized in a jet mill under nitrogen flow to an average particle size of about 5 μm. The resulting fine powder was filled into a die, oriented in a magnetic field of 15 kOe, and subjected to a pressure of 1.2 metric tons / cm applied perpendicular to the magnetic field. 2 compacted under pressure. The powder compacts thus obtained are...

Embodiment 3

[0059]The starting materials used are neodymium, terbium, electrolytic iron, cobalt, iron-boron alloys, aluminium, copper and titanium with relatively high carbon concentrations. For the dual alloy method, the master alloy is formulated to be composed by weight of 27.3Nd-balance Fe-0.5Co-1.0B-0.4Al-0.2Cu, and the auxiliary alloy is formulated to be composed by weight of 46.2Nd-17.0Tb- The balance is Fe-18.9Co-xTi (where x=0.2, 4.0, 9.8 or 25). The final composition after mixing is 29.2Nd-1.7Tb-balance Fe-2.3Co-0.9B-0.4Al-0.2Cu-xTi (where x=0.01, 0.2, 0.5 or 1.3) in weight ratio. Prepare master alloy by single roll quenching process, then at +0.5~+2.0kgf / cm 2 hydrogenated in a hydrogen atmosphere, and at a maximum of 10 -2 The half-dehydrogenation was carried out at 500° C. for 3 hours under Torr vacuum. The auxiliary alloy is made into an ingot by high-frequency melting and casting into a water-cooled copper mold.

[0060] Next, 90wt% master alloy and 10wt% auxiliary alloy...

technical field

[0001] The invention relates to a Nd-Fe-B based rare earth permanent magnet material. Background technique

[0002] Rare earth permanent magnets are commonly used in electrical and electronic devices due to their excellent magnetic properties and economy. Recently, demands for improving their performance continue to increase.

[0003] In order to improve the magnetic properties of R-Fe-B based rare earth permanent magnets, it is necessary to increase the R that exists as the main phase component in the alloy 2 Fe 14 B 1 phase ratio. This means reducing the Nd-rich phase which is a non-magnetic phase. This in turn requires reducing the concentration of oxygen, carbon and nitrogen in the alloy to minimize oxidation, carburization and nitriding of the Nd-rich phase.

[0004] However, reducing the oxygen concentration in the alloy creates the possibility of anomalous grain growth during sintering, resulting in high remanence Br, but...

Examples

Embodiment 1

[0047] Starting materials: neodymium, praseodymium, electrolytic iron, cobalt, iron-boron alloys, aluminum, copper and titanium formulated as 28.9Nd-2.5Pr-balance Fe-4.5Co-1.2B-0.7Al-0.4Cu by weight - a composition of xTi (where x = 0, 0.04, 0.4 or 1.4), followed by the preparation of the corresponding alloys by a single roll quenching process. Then put these alloys at +1.5±0.3kgf / cm 2 Hydrogenation in a hydrogen atmosphere, at a maximum of 10 -2 Dehydrogenation was carried out at 800° C. for 3 hours under Torr vacuum. Each alloy after hydrogenation and dehydrogenation is in the form of a coarse powder with a particle size of several hundreds of micrometers. Each of the coarse powders was mixed with 0.1 wt % stearic acid as a lubricant in a V-blender, and pulverized in a jet mill under nitrogen flow to an average particle size of about 3 μm. The resulting fine powder was filled into a die, oriented in a magnetic field of 25 kOe, and 0.5 metric tons / cm 2 compacted under pre...

Embodiment 2

[0053] Starting materials: relatively high carbon concentrations of neodymium, dysprosium, electrolytic iron, cobalt, iron-boron alloys, aluminum, copper and titanium formulated to be 28.6Nd-2.5Dy-balance by weight Fe-9.0Co-1.0B- The composition of 0.8Al-0.6Cu-xTi (where x=0.01, 0.2, 0.6 or 1.5) was used to compare the effects of different titanium additions, and then an ingot of the corresponding composition was prepared by high-frequency melting and casting into a water-cooled copper mold. The ingots were crushed in a Brown mill. Each coarse powder thus obtained was mixed with 0.05% by weight of lauric acid as a lubricant in a V-blender, and pulverized in a jet mill under nitrogen flow to an average particle size of about 5 μm. The resulting fine powder was filled into a die, oriented in a magnetic field of 15 kOe, and subjected to a pressure of 1.2 metric tons / cm applied perpendicular to the magnetic field. 2 compacted under pressure. The powder compacts thus obtained are...

Embodiment 3

[0059]The starting materials used are neodymium, terbium, electrolytic iron, cobalt, iron-boron alloys, aluminium, copper and titanium with relatively high carbon concentrations. For the dual alloy method, the master alloy is formulated to be composed by weight of 27.3Nd-balance Fe-0.5Co-1.0B-0.4Al-0.2Cu, and the auxiliary alloy is formulated to be composed by weight of 46.2Nd-17.0Tb- The balance is Fe-18.9Co-xTi (where x=0.2, 4.0, 9.8 or 25). The final composition after mixing is 29.2Nd-1.7Tb-balance Fe-2.3Co-0.9B-0.4Al-0.2Cu-xTi (where x=0.01, 0.2, 0.5 or 1.3) in weight ratio. Prepare master alloy by single roll quenching process, then at +0.5~+2.0kgf / cm 2 hydrogenated in a hydrogen atmosphere, and at a maximum of 10 -2 The half-dehydrogenation was carried out at 500° C. for 3 hours under Torr vacuum. The auxiliary alloy is made into an ingot by high-frequency melting and casting into a water-cooled copper mold.

[0060] Next, 90wt% master alloy and 10wt% auxiliary alloy...