Study On The Microstructures And Mechanicle Properties Of Extruded Zn-Mn Alloys

Zinc alloy has the advantages of low melting point,excellent processability,suitable mechanical properties,corrosion resistance in the atmosphere,low friction coefficient,good biocompatibility,low production cost and reusability.Therefor,zinc alloy has potential applications in copper alloy alternative materials,superplastic materials,biomedical materials and corrosion-resistant materials.Although zinc-based alloys have many advantages,there are few zinc-based alloys available in the industrial field At present,mainly Zn-Al-Cu-Mg and Zn-Cu-Ti.In recent years,Addition alloying element Mn to zinc were studied by people and found that addition of alloying element Mn can make zinc alloy has high temperature superplasticity,can improve zinc-alloy’s corrosion resistance,and can significantly improve the comprehensive mechanical properties of Zn-Mg-based biodegradable alloy.However,it has not been clearly understood aboat the relationship between the addition of trace alloying element Mn and the microstructure and room temperature mechanical properties of the Zn-Mn binary alloy.Therefore,in this paper Zn-xMn(x=0.1,0.4,0.5,1.3,1.6 wt.%)and Zn-xMn(x=0.2,0.4,0.7,1.4,2.0 wt.%)binary alloy rod have been prepared by indirect hot extrusion process at 150℃ and 200℃.Then the influence of alloying element Mn on the microstructure and room temperature mechanical properties of Zn-Mn binary alloys were studied by the means SEM,XRD and EBSD mechanical test,so that we can understand better aboat the relationship of Zn-Mn binary alloy composition,extrusion process,microstructure and mechanical properties.The results of the experiment are as follows:After adding of Mn element to Zn.MnZn13 second phase was formed in the casting process.After the low-speed indirect extrusion,when the content of Mn is low,the second phase of the crushed small particles is distributed in the form of stripes along the direction of extrusion,when the Mn content is higher,the crushed small particles and the coarse large particles are uniformly distributed at the grain boundaries of the matrix.The uniformly distributed second phase inhibiting the growth of dynamic recrystallized grains,relative to pure zinc,Zn-xMn binary alloy matrix grains have been significantly refined,and with the increasing of Mn content,the grain size of the alloy is refined gradually.After high-speed extrusion,the alloy structure showed a similar pattern.Among them,the average grain size of Zn-1.6Mn alloy matrix obtained at 150℃ and 1 mm/s is 1.1μm.The average grain size of Zn-2.0Mn alloy matrix obtained at 200℃and 1 mm/s is 1.2μm.And with the increase of Mn content,the texture strength of base surface first decreases and then increases.Zn-xMn binary alloy was indirect hot extrusion at 150℃ and 1mm/s,with the increase of Mn content,the tensile yield strength and tensile strength were decreased,and the elongation was first increased then slightly reduced.After high-speed extrusion,the alloy showed the same variation,but compared to low-speed extrusion,the strength is slightly higher and the plasticity is lower.The yield strength and tensile strength Zn-0.1Mn binary alloy extrude at the rate of 1 mm/s were highest 153 MPa and 208 MPa,the elongation of Zn-1.3Mn alloy is highest 1.24;The yield strength and tensile strength Zn-0.1Mn binary alloy extrude at the rate of 5 mm/s were highest were 212 MPa and 257 MPa,the elongation of Zn-1.3Mn alloy is highest 0.99.The compressive yield strength showed decreasing trend with the increase of Mn addition,205 MPa of Zn-0.4Mn was highest,and the tension-compression asymmetry of alloy decreases with the increase of Mn content.However,the strength and ductility of Zn-Mn alloys were significantly improved compared to pure Zn prepared under the same conditions.The tensile yield strength,tensile strength and elongation of the as-extruded Zn-xMn alloy obtained at 200℃ and 1 mm/s were increased firstly and then decreased with the increase of Mn content.After high-speed extrusion,the alloy showed the same variation,The strength of the zinc alloy obtained by the two extrusion rates is similar,but the alloy obtained by the at the low-speed extrusion rate has better elongation.The yield strength and tensile strength of Zn-0.4Mn binary alloy extruded at 1 mm/s were highest,135 MPa and 206 MPa,the elongation of Zn-1.4Mn alloy was highest,1.24.The yield strength and tensile strength of Zn-0.4Mn binary alloy extruded at 5 mm/s were highest,140 MPa and 203 MPa,and the elongation of Zn-1.4Mn alloy was highest,1.06.