Magnesium is one of the most abundant metal elements,which has been widely studied.Because of the poor corrosion resistance and formability of magnesium alloy,most scholars focus on how to improve the corrosion resistance and formability of magnesium alloy and for the characteristics of magnesium alloy corrosion are seldom used,especially on how to increase the corrosion rate of magnesium alloys for the application of degradable materials with high corrosion rates,the literature rarely reported in recent decades.In addition,Fe is one of the metal elements which cannot be dissolved in magnesium alloy but can effectively accelerate the corrosion rate of magnesium alloy.Therefore,this paper mainly studies a high rate magnesium matrix composites(xFe/Mg-6Al-1Zn)fabrication process and the effect of heat treatment on the microstructure,corrosion resistance and mechanical properties,and provides a theoretical basis for the preparation of degradable materials with a high corrosion rate.The main research contents and results are as follows:(1)Raw materials(xFe/Mg-6Al-1Zn)were prepared by powder metallurgy method.First,Fe,Mg,Al,Zn powders were mixed and grinded according to the corresponding proportion,the green were obtained by pre-compression forming under the pressure of 2500KN(h=76±1 mm,d=78±1 mm)inside hydraulic cylinder at room temperature;After preserve heat at 370℃for an hour,the xFe/Mg-6Al-1Zn(x=0,1,3,5,7)magnesium matrix composite extruded was obtained with a diameter of 16 mm.The extrusion ratio is 25:1.(2)The microstructure of the xFe/Mg-6Al-1Zn magnesium matrix composites extruded was observed.The dynamic recrystallization is not completed,the grain size is not uniform;the Fe is not soluble in the magnesium matrix,and is uniformly distributed in the magnesium matrix in the form of particles,and the second phase β-Mg17Al12 is distributed along the extrusion direction in the form of fiber type.The corrosion rates increased with the increase of Fe contents.When the contents of Fe was 7 wt.%,the maximum corrosion rate was about 2.4 ml h-1 cm-2.When the content of Fe was 3 wt.%,the maximum compressive strength was 384 MPa,however,the compressive stress-strain curves of the same components samples are poor coincidence and mechanical properties were not stable.(3)xFe/Mg-6Al-1Zn magnesium matrix composites after annealing 350℃ for an hour,the static recrystallization was completed and the grain distribution was not uniform.The second phase is reduced,and the distribution by fiber shape transform into block.The corrosion rate decreases after annealing,when the Fe content is 7 wt.%,the highest corrosion rate is about 1.75 ml h-1 cm-2,while the highest compressive strength of 370 MPa,high degree of coincidence of compressive stress-strain curves and stable mechanical properties were obtained.(4)xFe/Mg-6Al-1Zn magnesium matrix composites after 400℃solid solution for 12h+200℃ ageing for 8h.The grain growth,the second phase β-Mg17Al12 fibers shape disappeared and in a punctate form uniformly distributed in a magnesium matrix.The volume fraction and size of β-Mg17Al12 precipitated first increased and then decreased with the increase of Fe contents.When the Fe contents is 1 wt.%,the particle size of β-Mg17Al12 precipitated was the largest and the volume fraction was the highest.When the Fe contents is 7 wt.%,the maximum corrosion rates is about 22.6 ml h-1 cm-2,which is about 10 times higher than that of the extruded and annealed samples.However,the maximum compressive strength is about 355 MPa,and the mechanical properties are stable. |