Research On The Mechanical Properties Of Titanium-based Alloys Prepared Based On TiH₂

In this study,pure titanium and its alloys were prepared by vacuum powder metallurgy using titanium hydride powder,titanium powder and aluminium vanadium alloy powder as raw materials.The phase,microstructure,density and mechanical properties of sintered samples were analyzed,and the thermodynamics of elements and oxygen during vacuum sintering were discussed.The following conclusions were obtained:1 TC4 alloy was prepared from TiH2 powder at different sintering temperature and time.Its phase structure is dense hexagonal structure ?-Ti and body-centered cubic structure ?-Ti biphasic structure,However,with the increase of sintering temperature,p-Ti tends to decrease.The sintered samples show equiaxed,flaky or mixed structure.With the increase of sintering temperature and time,the equiaxed structure decreases,the flaky structure increases,and the structure coarsens.TC4 alloy specimens with relative density 96.9-99.6%,tensile strength 719.3-914.1MPa,elongation 6.2-9.4%and hardness 313.2-364.8MPa can be obtained by this method.The tensile strength of TC4 alloy specimens sintered at 1150 C for 1.5h is 914.1 MPa and elongation is 7.60-/o.The tensile fracture morphology of pure TiH2 powder and pure Ti powder sintered samples is dimple;the tensile fracture morphology of TiH2-6Al-4V samples is strip brittle fracture pattern and a small number of dimples;the tensile fracture morphology of Ti-6A1-4V samples is dimple,but the dimples are shallower than pure TiH2 powder sintered samples and pure Ti powder sintered samples,but the brittle fracture morphology is less than that of TiH2-6A1-4V samples.2 TC4 was prepared by using titanium hydride and titanium powder as raw materials at different heating rates.The sintered TC4 was composed of a+p biphasic phase,and the position of diffraction peak shifted to a large angle with the increase of heating rate.and the structure is composed of equiaxed and flaky structures.With the increase of heating rate,the flaky structure,tensile strength and elongation first increase and then decrease.Compared with the sample(TiH2-6A1-4V),the position of the diffraction peak of the sample(TiH2-6A1-4V)shifts to a larger angle;the compactness of the compact before sintering(TiH2-6Al-4V)is lower;the relative density of the sintered(TiH2-6A1-4V)sample is higher and more compact;the sheet structure of the sample(TiH2-6A1-4V)is easier to obtain;the tensile strength of the two samples is similar,but the elongation of the sample(TiH2-6A1-4V)is lower and comprehensive.The mechanical properties are poor.When the samples(TiH2-6A1-4V)and(Ti-6A1-4V)were sintered at 8?/min,the tensile strength was 889.73MPa,the elongation was 8.06%and the tensile strength was 899.06MPa,and the elongation was 9.16%.3 Using titanium hydride and titanium powder as raw materials,the micro structure and mechanical properties of titanium alloys with different Al-V contents were analyzed.The sintered samples of pure TiH2 powder and pure Ti powder are all ?-Ti.With the increase of alloying elements,the diffraction peak of?-Ti appears and shifts to a large angle,and the ratio of crystal axis increases.The sintered samples of pure TiH2 powder and pure Ti powder are equiaxed.After adding A1 and V alloy elements,TiH2 powder corresponds to the sintered sample and Ti powder corresponds to the equiaxed structure.The morphologies of the two kinds of alloys change little with the increase of A1 and V contents.The relative density of the corresponding samples sintered from TiH2 is higher than that of the corresponding samples sintered from Ti powder.The tensile strength of sintered pure TiH2 powder and pure Ti powder corresponding samples is 562.88MPa and 513.44MPa,respectively,with lower strength but higher elongation,28.15%and 29.09%respectively.With the increase of A1 and V content,the strength of TiH2 powder and Ti powder corresponding samples increases first and then decreases,with the maximum strength being 914.lOMPa and 937.23Mpa,respectively,and the corresponding elongation being 7.60%and 10.89%in Al,V,respectively.Under the same content of pure Ti powder,the elongation of sintered samples is slightly higher and the comprehensive mechanical properties are slightly better.The fracture morphology of the sintered TiH2 and Ti powders is typical dimples.With the increase of A1 and V contents,the brittle fracture morphology of the two alloys increases,the elongation decreases and the plasticity decreases.The fracture morphology of the two kinds of alloy specimens with Al-V addition is different.The morphology of TiH2 corresponding specimens is mainly strip pattern and a few dimples,while that of Ti powder corresponding specimens is mainly dimples.4 In this study,the formula for calculating the of each substance and oxygen is derived.According to the calculation results,A1,Ti and V are easily oxidized.Among the elements,A1 is most easily oxidized,and the order of other substances is Ti,V.Under these conditions,fewer oxides were formed and no oxygen pairs were detected.The main mode of oxygen pairs was the existence of interstitial elements.