Electron beam damage during testing of wood in the SEM

Summary Specimens of spruce (Picea abies) were taken to compression failure in the SEM while the backscattered electron imaging was used. Control specimens were taken to failure with no beam exposure. Failure morphology was studied using the secondary electron imaging. Wood exposed to the electron beam during testing showed a glassy fracture, while wood exposed to high vacuum but not to the electron beam showed a ductile fracture. There was found no evidence of any significant brittleness for unexposed wood at different moisture content levels. Although electron beam damage may be reduced, it can never be avoided. Caution is therefore to be exercised in the interpretation of results of compression tests in the SEM.