Method for press molding rare earth alloy powder and method for producing sintered object of rare earth alloy

1. A method for pressing and compacting a rare-earth alloy powder by using a die, the die being made of a non-magnetic material and having a die hole and a pair of yoke members, the die hole defining a cavity, the yoke members being provided on right- and left-hand sides of the die hole, the method comprising the steps of:

providing the rare-earth alloy powder;

filling the cavity of the die with the rare-earth alloy powder;

generating vibration in the rare-earth alloy powder; and

compressing the rare-earth alloy powder, which has been loaded into the cavity, between a pair of press surfaces that are opposed to each other, wherein

a pulse magnetic field, which is substantially perpendicular to a compressing direction, is not applied until the apparent density of the rare-earth alloy powder in the cavity reaches a predetermined value, which is at least equal to 47% of the true density thereof, while the compressing step is being carried out, and

the step of generating vibration in the rare-earth alloy powder is performed while the compressing step is being carried out and before the pulse magnetic field starts to be applied.

2. The method of claim 1 , wherein the predetermined value is defined at 3.55 g/cm 3 or more.

3. The method of claim 1 , wherein the pulse magnetic field is an alternating attenuating field.

4. The method of claim 1 , wherein the pulse magnetic field is an inverse pulse magnetic field.

5. The method of claim 1 , wherein the vibration is transmitted from at least one of the two press surfaces.

6. The method of claim 1 , wherein the rare-earth alloy powder is made by a rapid cooling process.

7. A method of making a sintered body of a rare-earth alloy, the method comprising the steps of:

making a compact of the rare-earth alloy powder by the method of claim 1 ; and

sintering the compact.