In order to examine the effect of grain boundary on fatigue life, aluminum bicrystals with a longitudinal boundary were prepared by the Bridgman method. They were tested by a bending fatigue testing machine under the constant strain amplitude of 0.13% and cyclic frequence of 30.4Hz. The results obtained were as follows:
(1) The fatigue life decreased with increasing the saturation moment, Ms, at N=103.
(2) The existance of grain boundaries in aluminum bicrystals possibly shortens the fatigue life.