Yongxiong Liu

Effect of Si on growth kinetics of intermetallic compounds during reaction between solid iron and molten aluminum

The effect of Si on the growth kinetics of intermetallic compounds during the reaction of solid iron and molten aluminum was investigated with a scanning electron microscope coupled with an energy dispersive X-ray spectroscope, and hot-dip aluminized experiments. The results show that the intermetallic layer is composed of major Fe2Al5 and minor FeAl3. The Al−Fe−Si ternary phase, τ1/τ9, is formed in the Fe2Al5 layer. The tongue-like morphology of the Fe2Al5 layer becomes less distinct and disappears finally as the content of Si in aluminum bath increases. Si in the bath improves the prohibiting ability to the growth of Fe2Al5 and FeAl3. When the contents of Si are 0, 0.5%, 1.0%, 1.5%, 2.0% and 3.0%, the activation energies of Fe2Al5 are evaluated to be 207, 186, 169, 168, 167 and 172 kJ/mol, respectively. The reduction of the activation energy might result from the lattice distortion caused by Si atom penetrating into the Fe2Al5 phase. When Si atom occupies the vacancy site, it blocks easy diffusion path and results in the disappearance of tongue-like morphology.

Experimental study of the phase relationships in the Al-rich corner of the Al–Si–Fe–Cr quaternary system at 700 °C

Abstract The phase equilibria of the 700 °C isothermal section of the Al–Si–Fe–Cr quaternary system with Al fixed at 90 at.%, and the related Al-rich ternary systems, have been determined experimentally with scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and X-ray diffractometry. Eight four-phase regions and a new quaternary compound named ζ are found in the 700 °C isothermal section of Al–Si–Fe–Cr quaternary system. The ζ phase is found to be in equilibrium with all phases in the section including the FeAl3, τ5, τ6, (Si), τ1, Al4Cr, Al45Cr7 and H phases, as well as the liquid phase.

Experimental study of the phase relations in the Fe–Cr–Si ternary system at 700°C

Abstract The 700°C isothermal section of the Fe–Cr–Si ternary phase diagram has been determined experimentally by means of scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and X-ray powder diffraction. Ten three-phase regions exist in the 700°C isothermal section. The binary σ phase contains 0–17.6 at.% Si and 31.4–59.2 at.% Cr; the Fe5Si3 phase is stable at 700°C because of the dissolution of Cr. At this temperature, Fe and Cr cannot be entirely substituted by each other to form the FeSi or CrSi phases: the maximum possible Cr content in FeSi2, Fe5Si3 and D03 is 3.9, 20.7 and 15.2 at.%, respectively, and the maximum soluble Fe in CrSi2, Cr5Si3 and Cr3Si is 2.5, 20.4 and 16.8 at.%, respectively.