Study of spark plasma sintered nanostructured ferritic steel alloy with silicon carbide addition
Abstract Pure nanostructured ferritic steel alloy (NFA) and NFA silicon carbide (SiC) composites with different compositions (97.5 vol% NFA 2.5 vol% SiC and 95 vol% NFA 5 vol% SiC) have been sintered by spark plasma sintering (SPS) and systematically investigated based on XRD, SEM, density, Vickers hardness, and nano hardness. Minor g Fe phase formation from the main a Fe matrix occurs in pure NFA between the sintering temperature of 950 degC and 1000 degC. However, this is hindered in the NFA SiC composite sintering. Densities for both the pure NFA and the NFA SiC composites increase with the sintering temperature but decrease with the SiC content. The NFA SiC composites have higher porosity than pure NFA under the same sintering condition. All the samples have the average grain sizes between 6 um and 8 um. Vickers hardness of the pure NFA and NFA SiC composites is related to density and phase composition. By estimation, the 97.5 vol% NFA 2.5 vol% SiC composite sample has the maximum yield strength of 3.14+ 0.18 GPa. Nano hardness of the NFA SiC composite is degraded by diffusion and reaction between NFA and SiC. The addition of SiC decreases the elastic modulus of the NFA SiC composites.