Investigation On Phase Equilibria Of The Fe-Ai-Sb Ternary System

For iron and steel parts, hot-dip galvanizing is an effective and economic methodto prevent atmospheric corrosion. Hot dip galvanized products have better workabilityand corrosion resistance, so this method has been widely used in many fields.In order to get a better coating organization in the process of actual production,We usually add some other alloy elements in the zinc pool. Aluminum is a kind ofvery important additive element, the coating could be improved in the toughness,bonding strength and workability after adding aluminum into the molten pool. Lead isalso a better additive elements, but because it is toxic, so we must use other elementsto replace it. The researchers have found Sb has similar function with Pb in a zincbath which not only promotes the formation of spangle in the coating surface andmakes the molten zinc more fluid but also makes the crystal particles smaller andreduce zincilate.In order to thoroughly understand the effect of aluminum, antimony and thesynergistic effect of them in galvanized process, deeply investigation on theFe-Zn-Al-Sb quaternary phase diagram and its thermodynamic relations should bedone to guide hot-dip galvanizing. At present, only the Fe-Al-Sb ternary alloy phasediagram has not been reported in the quaternary system, so it’s important to researchthe Fe-Al-Sb ternary system.The450°C,680°C and800°C isothermal sections of Fe-Al-Sb ternary systemhave been determined by scanning electron microscopy coupled with energy dispersespectroscopy, X-ray diffractometer and other relevant Experimental apparatus. Theresults indicate that there are Seven three-phase regions in the isothermal section at450°C, i.e., BCC_B2(FeAl)+FeSb2+FeSb, BCC_B2(FeAl)+FeSb2+AlSb,BCC_B2(FeAl)+FeAl2+AlSb, FeAl2+Fe2Al5+AlSb, Fe2Al5+FeAl3+AlSb,FeAl3+αAl+AlSb, αSb+FeSb2+AlSb. Seven three-phase regions have been foundexperimentally in the isothermal section at680°C, i.e., BCC_B2(FeAl)+FeSb2+FeSb, BCC_B2(FeAl)+FeSb2+AlSb, BCC_B2(FeAl)+FeAl2+AlSb, FeAl2+Fe2Al5+AlSb, Fe2Al5+FeAl3+AlSb, FeAl3+L-Al+AlSb, L-Sb+FeSb2+AlSb.The experimental results show that there are only six three-phase regions in theisothermal section at800°C, i.e., BCC_B2(FeAl)+L-Sb+FeSb, BCC_B2(FeAl)+ L-Sb+AlSb, BCC_B2(FeAl)+FeAl2+AlSb, FeAl2+Fe2Al5+AlSb, Fe2Al5+FeAl3+AlSb, FeAl3+L-Al+AlSb. According to the experimental results we can also knowthat the Fe-Al-Sb ternary system does not exist any new phase at450°C,680°C and800°C; the maximum solubility of Fe, Al and Sb in the related compounds haveincreased as the increase of temperature; the compound AlSb can not equilibrate withFeSb, BCC_A2but it can equilibrate with other phases.