The Role of Manganese on Nucleation and Growth of Vanadium Carbide in Iron-Based Composites

Vanadium carbide (VC) particle reinforced iron-based composites (VCFCs) with excellent wear resistance find multifarious industrial applications. One of the key factors that influence the microstructure chrematistics (shape, size and distribution) of vanadium carbide and texture of iron matrix is the Mn element. However, it remains unclear how the Mn element have an impact on the nucleation mechanism of the VC and structure of iron matrix. Here, we fabricated the VCFCs via adjusting the amount of Mn element and investigate how the concentration of Mn affects the microstructure chrematistics (shape, size and distribution) of vanadium carbide and texture of iron matrix, underlying the action mechanism of Mn on nucleation and growth of vanadium carbide, accompanied with texture of Fe-matrix. We demonstrate that diffusion of alloying elements is were restricted due to the addition of Mn element, and VC are transformed from thickly dendrite crystal with size of ~50 μm ( 1.5 wt.% Mn) to tiny equiaxed crystal with size of ~5 μm (4.5 wt.% Mn), furthermore nucleation mechanism of VC is also changed from homogeneous nucleation to heterogeneous nucleation owing to lower Gibbs free energy of TiC and tailoring effect of Mn element. In addition, γ-Fe of FCC structure is gradually increased attributed to lower transformation temperature of martensite (Ms) with the increase of Mn content.