Microstructure And Mechanical Properties Of Ti-1Al-8V-5Fe Sintered By Spark Plasma Sintering

Titanium and titanium alloys have high specific strength,excellent corrosion resistance and wear resistance,and are widely used in aerospace,automobile manufacturing,biomedical and other fields.Among them,the excellent comprehensive properties of β-titanium alloy have been paid more and more attention by scholars.However,the higher processing cost of β titanium alloy limits its further industrial development.Therefore,the development and application of low-cost β titanium alloys have received extensive attention and attention.The reason why β titanium alloy is not widely used is mainly because the elemental β stable element is expensive,and some βstable elements diffuse slowly.Traditional melting technology has an inhomogeneous alloy structure,which requires multiple melting,increasing the cost of preparation.Iron is a strong β-stabilizing element.The iron-containing alloy powder is used to replace the expensive β-stabilizing element vanadium,which reduces the cost of preparing the titanium alloy from the raw materials.Spark plasma technology,low sintering temperature,high sintering efficiency,effectively inhibits the growth of crystal grains during sintering,pressurizes during sintering,and has a high density of samples.The preparation of titanium alloy by spark plasma sintering can avoid the unevenness of the structure caused by element segregation.phenomenon.In this paper,Ti-1Al-8V-5Fe(Ti185)alloy is prepared by using sponge titanium and vanadium-iron alloy powder as raw materials,and discharge plasma sintering is performed.The density and microstructure of Ti185 alloy are studied by the size of vanadium-iron powder,sintering temperature and holding time.Influence of appearance,mechanical properties and wear resistance,draw the following conclusions:Spark Plasma Sintering(SPS)sintering temperature is 1150 ℃,holding for 10 minutes can make 5%(wt.%)Fe element in Ti85 mixed powder prepared by 325 mesh iron vanadium powder evenly diffuse,without causing "β speckle" due to the slow eutectoid of Fe and matrix Ti.Holding at a sintering temperature of 1150 ℃ for 30 minutes can make 8%(wt.%)V element diffuse uniformly,and the structure is composed of equiaxed α phase and β phase.At a sintering temperature of 1250 ℃ and 1350 ℃,holding for 15 minutes promotes the uniform diffusion of β-stabilizing elements,which is beneficial to the formation of β phase and increases the content of β phase.Continue to extend the holding time to 30 min,the primary isometric α phase in the tissue decreases sharply,In the β-transformed structure,secondary needle-like α phases are precipitated in large amounts,and an equiaxed structure composed entirely of β phases is obtained.The high sintering temperature of 1350 ℃ ensures that the slow diffusion element V can be evenly distributed,and the short holding time of 10 min prevents the crystal grains from being too large,which can ensure the best mechanical properties of the alloy: elastic modulus 17.95 GPa,ultimate compressive strength 2004 MPa with a compression rate of27.1%.When holding for 30 minutes,at three sintering temperatures of 1150 ℃,1250 ℃and 1350 ℃,the samples have the same phase composition,and the main constituent phases are both α-phase and β-phase.At 1150 ℃,the content of β tissue is much higher than that of α phase,and there is less α phase precipitated in β transition phase of the tissue.The sample structure is mainly composed of β phase and primary equiaxed α phase.Adding 150 mesh,325 mesh,600 mesh iron vanadium powder,and holding the sample at 1150 ℃ for 10 min.After annealing and heat treatment,it is beneficial to the diffusion of V atoms in the center of the unmelted particles,reducing the number of refractory V metal particles,and diffusing V elements.The "β speckle" produced by unevenness has a certain improvement effect,although the segregation is not eliminated,but the compressive strength and plasticity of the alloy are enhanced.The solution heat treatment at 950 ℃ has a certain improvement effect on the segregation of V element,but the segregation is not eliminated.At the same time,after the solution treatment,the compressive strength of the alloy decreases and the plasticity increases.After holding for30 minutes,at different sintering temperatures,the depth of the wear scar profile of the sintered sample at 1350 ℃ was shallower and the width of the wear scar was narrower.The overall wear surface was smoother,with only slight furrows and sticky marks,and the wear mechanism showed a slight abrasive wear and adhesive wear.