Ultramicotomy means sectioning
a sample with the cutting edge of a diamond knife. The fracture is
initiated by the knife and propagates parallel to the surface without
disruption of the sectioned slice.
The technique suits for all types of single phased or multiphased materials, provided that hardness and/or fragility are not too important. It is usually performed on a small area (<1 mm²).
It consists in a support carrying the knife and a sample holder installed on a vibration proof platform. Both knife and sample have adjustable orientations. The knife is made of glass or diamond with a 35-45° angle. The sample is mounted on a vertically moving arm moving regularly against the knife edge. The device is equipped with a micro- to nanometer scale movement system controlling the object position. The relative position of the knife to the sample, cutting speed and desired thickness can be adjusted.