Microstructural characteristics and second-phase particles in yttrium-bearing Fe-10Ni-7Mn martensitic steels

In this study, the microstructure and second-phase particles in yttrium (0.05 wt.% and 0.8 wt.%) bearing Fe-10Ni-7Mn steels were characterized. The results of X-ray analysis as well as scanning electron microscopy coupled with energy dispersive X-ray spectroscopy indicated the formation of (Fe, Ni, Mn)17Y2 precipitates with hexagonal structure in a Fe-10Ni-7Mn-0.8Y (wt.%) alloy. Lattice parameters of these precipitates were calculated as follows: a=0.8485 nm and c=0.8274 nm. Formation of Y2O3 sub-micron particles was also confirmed in both yttrium bearing steels via electrolytic phase extraction method. The effect of these precipitates on the prior austenite grain size was investigated. The results revealed that these precipitates had an effective role in controlling the prior austenite grain size.