Effect Of Rolling Deformation And Heat Treatment On Microstructure And Properties Of Al-3Fe(Wt.%) Alloy

Al-Fe alloys were a kind of alloy with excellent properties such as heat resistance,abrasion resistance,and corrosion resistance.Al-Fe alloys were widely applied in many industrial fields.However,the Al3Fe phase morphology of conventional melt-casting Al-Fe alloys were coarse.The coarse Al3Fe phase severely splited the matrix,resulted in poor mechanical properties of Al-Fe alloys,thus limited the wide application of Al-Fe alloys.In this paper,the Al-3Fe(wt.%)alloy was prepared by continuous rheological extrusion.Rolling deformation and heat treatment of Al-3Fe(wt.%)alloy were carried out.The influence of cold rolling and heat treatment on the microstructure and properties of Al-3Fe(wt.%)alloy was studied.The method of refining Al3Fe phase was explored to improve the strength and elongation of Al-3Fe(wt.%)alloy.The following main results were obtained:(1)The evolution regularity of microstructure in Al-3Fe(wt.%)alloy during rolling deformation was obtained.During the rolling deformation of Al-3Fe(wt.%)alloy,the Al3Fe phase of the alloy was deformed and broken.During the rolling process,intense deformation occurred in the alloy.The original grains were elongated along the rolling direction,dislocation density increased,and the content of small-angle grain boundary increased.With the increase of deformation,the small-angle grain boundary gradually transformed into stable large-angle grain boundary,and the content of small-angle grain boundary gradually reduced.The grain of alloy was refined.After 5 passes of rolling deformation,the grain size of alloy was reduced from the initial 11.2 ± 0.56 μm to 2.5±0.13μm.(2)The variation of mechanical properties of Al-3Fe(wt.%)alloy during rolling deformation was obtained.The rheo-extruded pure Al and rheo-extruded Al-3Fe(wt.%)alloys were deformed by the same 5 passes rolling deformation.The mechanical properties of pure Al and Al-3Fe(wt.%)alloys were compared.The effect of nano Al3Fe phase on the mechanical properties of alloy was obtained.The tensile strength of pure Al increased from 52 MPa to 153 MPa after rolling.The tensile strength of Al-3Fe(wt.%)alloy increased from 162 MPa to 281 MPa.The increase of tensile strength of Al-3Fe(wt.%)alloy was higher than that of pure Al after rolling.It showed that nano Al3Fe phase played an important role in improving the strength of Al-3Fe(wt.%)alloy.With the increase of rolling pass,the elongation of pure Al and Al-3F e(wt.%)alloy decreased first and then increased,and the elongation of Al-3Fe(wt.%)alloy was always lower than that of pure Al.(3)The evolution of microstructure of Al-3Fe(wt.%)alloy during heat treatment was obtained.During the heat treatment at 200℃ and 300℃,the Al3Fe phase of the alloy was diffused,fused and granulated.With the prolongation of holding time,the size of Al3Fe phase was continuously decreased.Al3Fe phase had not been coarsened or grown up.During the heat treatment at 400℃ and 500℃,the Al3Fe phase was diffused,fused,granulated and coarsened,and with the prolongation of holding time,the size of the Al3Fe phase decreased first and then increased.(4)The variation of mechanical properties of Al-3Fe(wt.%)alloy during heat treatment was obtained.With the extension of holding time,the tensile strength of as-cast Al-3Fe(wt.%)alloy increased slightly,and the elongation varied from 16.4%to 17.8%.The effect of the heat treatment on the mechanical properties of as-cast Al-3Fe(wt.%)was not obvious.With the extension of holding time,the tensile strength and elongation of rheo-extruded Al-3Fe(wt.%)alloy decreased.However,during the heat treatment at 200℃ and 300℃,the tensile strength and elongation of alloy decreased slightly.During the heat treatment at 400℃ and 500℃,in the early stage of the heat treatment,the tensile strength and elongation of alloy decreased greatly.With the extension of holding time,the tensile strength and elongation of alloy decreased slightly and tended to be stable gradually.But the tensile strength and elongation of rheo-extruded Al-3Fe(wt.%)alloy were always better than the tensile strength and elongation of as-cast Al-3Fe(wt.%)alloy.