抄録
Yield load and hardness on nanoscale have been reported using nanoindentation. However, the effect of crystallographic planes on the yield load and the hardness is not well understood. In order to investigate the effect of the crystallographic planes on the yield load and the hardness of the metals in nearly perfect crystal, nanoindentation test is performed on (111), (110) and (100) planes of aluminum single crystal with 99.9999% ultra-high purity. The yield load at a loading stage is found to be closely related to the crystallographic plane. The yielding behavior is also observed at an unloading stage under some conditions. In the loading stage, two kinds of yield processes, minor and major burst, are observed on (100) plane. The critical shear stress is estimated from the yield load in the loading curve. The estimated stress shows close agreement with the ideal strength of aluminum. The relationship between the hardness and the crystallographic plane is investigated by means of nanoindentation and micro-indentation. The hardness is strongly affected by crystallographic planes on the nano-scale, and the result is discussed from a viewpoint of the appearance of the slip line and the pile up around the indent.
