Mechanical properties of a nanocrystalline Fe 20Cr 10Ni alloy prepared by in situ consolidation followed by severe deformation were investigated using microhardness and shear punch tests (SPT). The nanocrystalline alloy with a nominal Cr content of 20 wt% and Ni content of 10% was prepared by high-energy ball milling. The low strain hardening observed in nanocrystalline materials is shown to dramatically decrease ductility in both tension and compression. Crack nucleation or propagation instability requires an external source to supply enough stress at a crack tip to overcome or exceed the critical toughness value. Microhardness of the small discs was found to be 7.8 GPa which is at least 6 times greater than conventional grain size stainless steel of similar composition. Yield strength determined from the SPTs is found to be 2.6 GPa, which is consistent with the yield stress determined by microhardness tests.