Abstract
The characteristics of the percussion figures on single crystals of aluminium and copper were studied at room and high temperatures. First, the proper conditions to make the figures were surveyed to get the best experimental data. Needles of the top angles of 45° for aluminium and 30° for copper gave the best results. Next, the orientation relationship between the patterns developed and the crystal surface was examined. According to the surface orientation of crystal, petaloid figures and several kinds of slip traces were observed in general, and the latters are interpreted as being the surface traces of the usual slip planes {111}, and there were always observed three or more traces of equivalent planes (max. 4 when the usual slip systems of face-centered cubic metals, i.e. {111}-⟨110⟩ are operative). Using these three directions of slip traces, the orientation of a crystal can be easily determined by means of crystal globe, even in the case of comparatively a small crystal grain.
