backscattered electrons. The last depends on the atomic number and weight as well as on the 
density of the material and on the energy of the electrons [93Joy]. Little is known about the exact 
050 information depth of EBSD. Since only low loss backscattered electrons contribute it is much 
rt ? lower. Comparing with Monte Carlo simulations for some materials it is approximately a forth for a 
cut-off energy of 90 % [98Ren]. Some of the obtained EBSPs are shown in the graph with their 
: PQI, other are omitted for clarity. 
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= H P u Fig. 5: Test materials differing in hardness and EBSD information depth; R(BS) corresponds to the 
tT escape depth of the backscattered electrons at 20 kV; R(EBSD) is about 25 % of R(BS). EBSP of 
some materials are included with their PQ] 
As mentioned above in the most cases the standard preparation procedures must be modified for 
EBSD. As a general guideline reduced loads and rotation speed should be used for mechanical 
grinding and polishing. The final step can be performed in different ways that would depend on the 
material. Those a summarised in Fig. 6. Often vibratory polishing with colloidal silica is among the 
best solutions. The polishing time can be of about some hours. Therefore polishing cloths should be 
chosen very carefully in order to avoid relief on the specimen surface. If such equipment is not 
available normal rotation polishing with silica could also provide acceptable results. Some etchant 
may be used for speed. Chemical polishing and slight etching are very fast and they surely remove 
any residual distortion. But care should be taken to avoid surface layers as well as pitting and/or 
severe roughening. Another very recommended method is electropolishing. Again, no surface layer 
should be left. Unfortunately electropolishing is restricted to electrically conductive materials. 
Some physical methods are very useful for ‘difficult’ materials like ceramics, minerals or metals 
with high oxygen affinity. Especially oxidation layers should be avoided — therefore annealing of 
test materials metals for example should take place in inert gas atmosphere or in vacuum. Beam energies if using 
1 their EBSD ion beam or reactive plasma should be rather low to avoid additional damage. 
wont of 16 Details on the preparation for the materials included in Fig. 5 will be given elsewhere [00K at]. 
BaTIU 
357