SEM images of LiF heated by SPS to 500 °C at 2 MPa. (a) Melting of the particle corners, (b) surfaces wetted by a flowing liquid and (c) the material jet formed by the spark impact are visible.Cuboidal LiF microcrystal powder was densified by spark plasma sintering at different pressures up to 500 °C. Densification at pressures above the yield stress occurred by plastic deformation and strain hardening. Densification at 2 MPa, below the yield stress, occurred by particle rearrangement assisted by viscous flow at the particle surfaces. Scanning electron microscopy examination of the fracture surfaces of the partially dense specimens revealed partial melting of the particle surfaces due to the plasma. The onset temperature for plasma formation was ∼180 °C.
This paper was originally published in Scripta Materialia, 82 (2014), Pages 57-60.
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