Martensitic Transformation from Nanocrystalline Austenite in Fe-Ni Alloys Fabricated by Electrodeposition

Abstract

In this work, we fabricated nanocrystalline austenite structures of Fe-Ni alloys by electrodeposition and subsequent heat treatment, and investigated the martensitic transformation behavior from the nanocrystalline austenite. The martensite transformation start temperature of the nanocrystalline austenite with a grain size of 224 nm was significantly lower than that of a coarse-grained austenite. The morphology of the martensite transformed from the nanocrystalline austenite was equiaxed and totally different from lenticular plate martensite and thin plate martensite that usually form from coarse-grained austenite. The martensite contained transformation twins with average twin width of 2.2 nm. The orientation analysis revealed that the martensitic transformation from the nanocrystalline austenite was accompanied with the formation of several martensite variants.