Non-isothermal Crystallization and Thermal Transformation Behaviors of Plasma Sprayed Fe48Cr15Mo14Cl5B6Y2 Amorphous Coating

The non-isothermal crystallization dynamic behavior and mechanism of plasma sprayed Fe48Cr15Mo14C15B6Y2 coating were thoroughly studied. The phase transition and crystallization kinetics of the coating were elaborately investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The findings reveal that the characteristic temperatures of the coating shift to an elevated temperature at a higher heating rate and the crystallization processes are thermally activated. The 3-rd step of crystallization processes is more susceptible to the continuously increased heating rate while the onset crystallization reaction is less sensitive to the continuously enhanced heating rate. Fe23(C, B)6 phase is inclined to precipitate than other crystal phases due to the substantial pre-generation of alpha-Fe. The onset nucleation and growth of alpha-Fe crystals is tough due to a higher onset apparent activation energy. Meanwhile, the transformation from Fe23(C, B)6 to FeB is harder in comparison with the precipitation of other crystals. The most parts of the three crystallization processes are dominated by three-dimensional diffusion model due to the fact that most values of local Avrami exponent are higher than 2.5.