Development of eco-materials by using nano-structure analyses with neutron scattering

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Microstructure evolution and strengthening mechanisms of severely drawn steel wires with various carbon concentrations up to 0.9 mass% were examined by means of neutron scattering. Texture, Intergranular stress, grain size and dislocation density were analyzed by a profile analysis for neutron diffraction, which was newly developed in this study. The grain size of 0.9C steel becomes several ten nanometers that is consistent with TEM observations. The merits to use neutron diffraction is to obtain bulky averages of micro-factors which are well connected with mechanical behavior. The mutli-scaled heterogeneity in microstructure as well as deformation behavior of as-patented pearlite and its drawn wires have been made clear.Phase transformation behaviors of steels were studied in situ by neutron diffraction. The in situ diffraction during athermal martensitic transformation in a 30Ni-0.2C steel during cooling and tempering reveals the change in c/a of bct martensite with low temperature t … More empering. Diffusional transformation from martensite to austenite upon heating and then austenite to ferrite and pearlite transformations was studied in situ and carbon enrichment, lattice strain (internal strain), volume fraction etc can be found. Thermo-mechanically controlled process was firstly investigated under neutron diffraction. The effect of austenite deformation on phase transformation and grain refinement are discussed by using direct experimental data.Nano-scaled nitrogen ordered zone was evaluated by small angle scattering in austenitic stainless steels with several amounts of nitrogen contents. In situ neutron scattering was performed for large angle (Bragg) and small angle neutron diffraction and the intergranular stress and destroy of short range ordering were found. These new findings have revealed the mechanisms of high performance in nitrogen bearing steels.These materials are all aimed at realizing ecomaterials and further related investigations have been started based on the present results. Less