Research Of Microsturcture And Property Of Al-Fe Alloy Prepared With The Plasma Injection Technology

This article reviewed the Al-Fe alloy research status at home and abroad, on the basis of forefathers' research on innovation proposed the plasma injection technology for the preparation of Al-Fe alloy, through the Fe/Al system of chemical thermodynamics and kinetics of calculation, the theoretical feasibility of the approach, and in the experiments to verify. In the view of the Fe content, aluminum liquid temperature, working current to study the influence of experimental parameters for exploring the influence law, by Ni elements added to improve the microstructure and performance of Al-Fe alloy, heat treatment experiments for the further processing of materials and study its thermal stability.Results show that Al₃Fe alloy phase prepared by plasma injection method was generated by in-situ reaction. Al₃Fe exist angular and fine need-like two kinds of forms, angular Al₃Fe generated by in-situ reaction of liquid aluminum and Fe powder, fine need-like Al₃Fe generated by dissolved Fe in the formation of precipitation during solidification.Al₃Fe volume fraction in alloy was directly related to Fe content, the Al₃Fe volume fraction grown with the growth of Fe content, increased the density, hardness and tensile strength of Al-Fe alloy. But the higher the Fe content, the elongation of the alloy was lower,and the more easily lead to high viscosity of the alloy liquid and blowholes of the alloy.Aluminum liquid temperature has great influence on microstruture and mechanical properties of Al-Fe alloy, the higher of the aluminum liquid temperature, the more bulky of the Al₃Fe, and was easily lead to long needle growth, resulted to serious loss of the mechanical properties of the alloy. For Al-10%Fe alloy, when the aluminum liquid temperature was less than 800 oC, the size of Al₃Fe was small and the performance of the alloy was good.Working current has good effect for spheroidizing, heating and accelerating the Fe powder, which could promoted the reaction of the Fe powder with liquid aluminum, but when the working current was too higher, the long needle growth trend of Al₃Fe was increased. For Al-10%Fe alloy, working current was 200A³00A relatively appropriate.Ni elements has a good effect for improving the microstruture and performance of Al-Fe alloy. The study found that the addition of Ni would generated Al₉Fe Ni, thus inhibited the formation of the fine need-like Al₃Fe, reduced the sharp angle of the angular Al₃Fe and refined the angular Al₃Fe, the refinement mechanism of the Ni elements lies in its would dissolved out together with the Fe elements which dissolved in liquid aluminum when solidification, due to occupy the position of Fe, Ni elements frustrated Al₃Fe needle-like growth way, therefore, Al₃Fe too late to grow into needle-like and solidification down,resulted in fine particle Al₃Fe. But too much of Ni content will lead to Al₉Fe Ni organization into rough, for Al-10% Fe alloy, Ni elements controlled under 2% was best.Homogenizing annealing could reduced the content of fine need-like Al₃Fe, has good effect for improving the elongation of Al-Fe alloy, but would caused slightly lower to the mechanical properties of alloy, which has a connection to the grain grow up of the alloy.Thermal stability experiments show that the Al-Fe alloy has a strong heat stability, for this material, after 640 oC high temperature annealing for a long time, the extent of Al₃Fe grew up was still small, and without long needle-like growth, and the addition of Ni element could further improved the thermal stability of material, this related to Ni element to form tiny dispersoid.