M50 nanostructured steel - The chemical synthesis and characterization of powders and compacts

Three different chemical routes have been investigated for the synthesis of nanostructured M50 steel. One method involves the ultrasound decomposition of organometallic precursors, the second method is the thermal decomposition of these precursors and the third is the co-reduction of metal halides using a reducing agent. These powders have further been compacted by vacuum hot pressing. The compacts are crystalline as evidenced by the peaks corresponding to bcc α-Fe, and the average grain size in the compacts was determined to be ≈30 nm by line broadening analysis. SEM/EDAX measurements on the powders and the compacts revealed a homogenous microstructure, with low porosity. TEM and electron diffraction were also performed on the compacts. The consolidated samples had a hardness of VHN 871 as compared to a hardness of VHN 800 for conventional, M50 steel. The samples had a high yield strength and modulus of elasticity.