Tensile and bending deformation of Ni3Al heavily cold-rolled foil

Local deformation characteristics of 95% cold-rolled Ni3Al foils were examined in tensile and bending tests along the rolling direction. The foils fracture without appreciable elongation in the tensile tests, while deform to 93° without cracking in the bending tests. However, the local deformation and fracture appear similarly in both of the tests: plastic deformation occurs in local regions by slip on the {111} planes where the slip deformation dominantly occurred during the prior cold rolling; cracks initiate along the shear bands which were formed during the cold rolling. The similarity of the local deformation was quantitatively confirmed by strain distribution measurements, i.e. the peak strain amounts to ∼10% just after crack initiation in both of the tests. These measurements verified that the extent of the local deformation is large enough to yield the good ductility in bending tests and not in tensile tests.