The Overshooting Phenomenon in Intermetallic Compound Ni3Al Single Crystals Tested in Tension

The lattice rotation and operative slip systems at each deformation stage were examined by tensile testing at various temperatures from 77 to 1073 K to make clear the contribution of secondary slip systems to the plastic deformation of Ni3Al single crystals. The overshooting phenomena were observed below 673 K, and after the overshooting the conjugate slip system operated below 296 K. The contribution of secondary slip systems to deformation was small at low temperature, but increased with increasing strain and temperature. Although the work hardening rate showed the positive temperature dependence, the latent hardening did the negative one. The work hardening of Ni3Al consists of two mechanisms; namely, one is the orientation and temperature dependent one, which causes the positive temperature dependence by the Kear-Wilsdorf mechanism and has no direct bearing on the latent hardening and the other is independent of the positive temperature dependence, which contributes to the latent hardening.