Morphology and orientation relationship of VC precipitates in HSLA steel

The morphology and distribution of VC precipitates in HSLA steel as well as the orientation relationship between VC precipitate and α-Fe were studied by transmission electron microscopy (TEM). The chemical composition of the VC precipitate was analyzed qualitatively by using analytical electron microscopy (AEM) equipped with an energy dispersive spectrum (EDS) system. The VC precipitate is needle-like in shape with a size of about 10 nm in length and is homogeneously dispersed in the α-Fe matrix. The smaller lattice misfit along the <100> lattice direction of α-Fe matrix leads to VC precipitate forming with its long axes nearly parallel to the <100> lattice direction of α-Fe matrix. It is confirmed that the orientation relationship between VC precipitate and α-Fe is the “N-W” orientation relation by selected area electron diffraction (SAED) patterns.