Microstructure And Corrosion Resistance Of Fe-Cr-Si Ternary Alloy Materials

Fe-Cr-Si alloys with high hardness and good corrosion resistance can become the novel corrosion-resistant materials.Fe-Cr-Si alloy was prepared by arc melting process and the microstructure of Fe-Cr-Si alloys was investigated.The electrochemical properties and corrosion resistance of Fe-Cr-Si alloys in HCl solution were tested.The polarization curves,corrosion kinetics curve,surface morphology and corrosion products of Fe-Cr-Si alloys were obtained.Taking Fe20Cr10Si as an example,high temperature oxidation experiments have been carried out in the atmosphere of 800℃and 900℃.The oxidation behavior of the alloy at high temperature was summarized by analyzing the oxidation kinetics curve of the alloy and the distribution of phase composition elements of the oxidation products.Results shown that the Fe-Cr-Si alloys are composed of primary dendrite and interdendrite matrix,and metal silicide Fe₃Si formed in the microstructure with the Si content in powder mixture increased to 10wt%.In the electrochemical experiment of HCl solution,the alloy has a wide passivation range and still has a stable passivation film at a higher voltage.The formation of Fe₃Si metal silicide and solution strengthening of Cr and Si can improve the corrosion of Fe-Cr-Si alloys in 10%HCl solution.The corrosion products mainly exist in the stable form of Cr Si Fe oxides and hydroxides which prevent the formation and further growth of pitting pits on the surface of the alloy.The oxidation resistance of Fe20Cr10Si alloy is more than 30 times of 0.45 C%steel in two kinds of high temperature,especially the formation of Fe₃Si metal silicide and Cr₂O₃,Si O₂,Fe₂O₃oxides further improve the oxidation resistance of the alloy.The mismatch between the thermal expansion coefficient of the oxide layer and the matrix leads to the cracking and spalling of the oxide layer,but then the matrix will be reoxidized.The reoxidation product of the alloy at 800℃is mainly Cr₂O₃,while the reoxidation product of the alloy at 900℃is a composite oxide layer of outer Si O₂and inner Cr₂O₃.Figure 36;Table 6;Reference 73...