Plasticity of Nanocrystalline BCC Iron Fabricated by Severe Plastic Deformation by Friction

Using nanoindentation technique, relationship between the microstructure and the mechanical parameters such as hardness, H-h, and plasticity characteristic, delta(A), are found to be actually dependent on the grain size of alpha-Fe samples subjected to severe plastic deformation by friction in argon atmosphere. Unlike f.c.c. metals, in which the decreasing of grain size to 20 nm results, in hardness rise only, and plasticity goes down,. there is a reverse effect in b.c.c.-Fe, namely, the decreasing of grains sizes from 50 to 20 nm causes the decrease of hardness from 5.8 to 3.7 GPa and increase of plasticity characteristic, delta(A), from 0.82 to 0.87.