Non-conventional Field Assisted Sintering (FAST|SPS) Of Permanent Magnet Materials

Field assisted sintering technology|spark plasma sintering (FAST|SPS) is an attractive alternative method for the processing of magnet materials starting from the respective powders. Combination of direct Joule heating in a conductive die and the application of uniaxial pressure enables controlled densification of magnet materials with short cycle times. We develop non-conventional modes of FAST|SPS operation specifically adapted to magnet materials including hot deformation of pre-sintered compacts – also known as spark plasma texturing (SPT) – and high-pressure FAST|SPS. The potential of SPT will be demonstrated on the example of a commercial melt-spun Nd-Fe-B powder. High-pressure FAST|SPS is also applied to processing of rare-earth free MnAl magnets. We present preliminary results of densifying a MnAl powder at moderate temperatures up to 600°C and pressures up to 1000 MPa. Advantages, boundary conditions and challenges of both methods will be discussed and compared with conventional processing.