The Effect Of Iron Content On The Structure And Properties Of Spray-deposited Continuous Extrusion High-silicon Aluminum Alloy

In the study,five different of components of hypereutectic Al-20Si-xFe（x=0,2,3,4,5）were prepared by spray Conform（SC）and conventional casting techniques,respective.The microstructures,tensile properties and wear behaviors of the alloys at room and elevated temperatures have been studied by optical microscopy（OM）,scanning electron microscopy（SEM）,X-ray diffraction analysis（XRD）,universal tensile testing machine,Gleeble 3500thermal simulation testing machine,pin-on-disk tribometer and Other test equipment,in this investigation.The results show that the size and distribution of the alloy prepared by SC technology,mechanical properties and wear resistance have been greatly improved.Studies have shown that the iron-rich phases present in the cast alloy are mainlyβ-Al₅FeSi andδ-Al₃FeSi₂ phases,but the iron-rich phases present in the SC alloy are mainlyβ-Al₉Fe₂Si₂andδ-Al₉FeSi₃ phases.Compared with the traditional cast,the microstructure of the hypereutectic Al-Si-Fe alloy in the SC is effectively refined and the distribution is more uniform.The size of the iron-rich phase is also reduced to a great extent while the iron-rich phase in the alloy is arranged parallel to the extrusion direction（axial direction）.Among them,with the increase of Fe content,the size of primary silicon particles in the alloy gradually decreases.Compared with alloys containing Fe and without Fe,the tensile properties of alloys with Fe added are greatly improved,especially the tensile strength of the alloy.The SC technique increased the tensile strength of the cast Al-20Si alloy from 91 MPa to 192 MPa,and after adding2 wt.%Fe,the tensile strength of the SC-Al-20Si alloy increased to 210 MPa.Compared with cast alloys,the tensile strength of SC alloys is twice.As Fe content increases from 2wt.%to5wt.%,the room-temperature tensile strength of SC alloy increases from 210MPa to 367MPa,and the elongation at break decreases from 2.89%to 0.52%.The tensile strength at room temperature is much higher than the high temperature tensile strength,which is about 1.5 times the high temperature tensile strength,but the elongation at break is only about 15%of the high temperature elongation at break.With the increase of Fe content,the high-temperature tensile strength of the alloy also increases,from 142MPa to 192MPa;the elongation at break decreases from 11.4%to 7.2%.SC technology can improve the wear properties of the alloy.The wear resistance of alloys prepared by SC technology is greatly improved compared with as-cast alloys.The wear rate of SC-state alloys can be reduced to as much as 50%of the as-cast and to 70%of the as-cast.And with the increase of Fe element in the alloy,the wear rate of the SC alloy decreases.Compared with the high temperature wear rate of the alloy,the room temperature wear rate shows a good performance.When the Fe element content is 4%,the wear rate of the alloy at room temperature and high temperature is very close.