Characterization of local deformation behavior of Fe–Ni lenticular martensite by nanoindentation

A Fe–33 mass% Ni alloy with transformed lenticular martensite consisting of various lattice defects was investigated by the nanoindentation technique. The highly dislocated regions such as the untwinned region and the austenite phase near the M/A interface showed a relatively easy plasticity initiation and lower flow stress than that of the midrib region containing fine transformation twins. The different responses of plastic deformation in the ultra-fine twins and the dislocated regions provided an insight into the local deformation response in various substructures during the nanoscale mechanical measurements.