The sizing and mechanical testing of whiskers of α-Al2O3

This paper describes procedures for (i) the sizing and orientation determination of `whiskers' using an interference microscope and (ii) the evaluation of the mechanical properties of whiskers using a Techne micro-tensile tester. The Young's modulus of α-Al2O3 whiskers can be markedly affected by both small tapers in the whisker shape and extraneous extensions occurring in the grip adhesive. Taper error can apparently increase the modulus by more than 100%, while extraneous grip-adhesive extensions decrease the modulus proportionally with decreasing gauge length. It is concluded that the Young's modulus of α-Al2O3 whiskers matches that for bulk single crystals of α-Al2O3 and that this value differs only slightly for various growth directions.