Wrought and laser powder bed fusion(LPBF)Ti−6Al−4V(Ti-6-4)specimens were comparatively evaluated,with the objective to determine LPBF Ti−6Al−4V’s suitability for biomedical applications.Testing included nanoindentati...Wrought and laser powder bed fusion(LPBF)Ti−6Al−4V(Ti-6-4)specimens were comparatively evaluated,with the objective to determine LPBF Ti−6Al−4V’s suitability for biomedical applications.Testing included nanoindentation,cyclic polarization in simulated body fluid(SBF,37°C),and dry and SBF“ball-on-plate”sliding.Wrought Ti-6-4 exhibited a lamellarα+βmicrostructure,whereas LPBF Ti-6-4 displayed a fine-grainedα′-martensite microstructure.LPBF Ti-6-4 demonstrated~3%higher indentation modulus and~32%higher hardness,while wrought Ti-6-4 showed~8%higher plasticity.Both alloys exhibited low corrosion rates(10−5 mA/cm^(2)order)and true passivity(10−4 mA/cm^(2)order).No localized corrosion was observed in either two alloys,except for occasional metastable pitting in the LPBF alloy.However,LPBF Ti-6-4 presented higher corrosion rate and passive current,ascribed to its martensitic structure.During dry sliding,LPBF Ti-6-4 exhibited~14%lower volume loss compared to wrought Ti-6-4.Sliding in SBF increased volume losses for both alloys,with wear resistances nearly equalized,as the advantage of LPBF Ti-6-4 decreased due to more intense wear-accelerated corrosion induced by the stressed martensite.Overall,the results demonstrate the suitability of LPBF Ti-6-4 for biomedical uses.展开更多
The novel cast irons of chemical composition(wt%)0.7C-5W-5Mo-5V-10Cr-2.5Ti were invented with the additions of 1.6wt%B and 2.7wt%B.The aim of this work was to study the effect of boron on the structural state of the a...The novel cast irons of chemical composition(wt%)0.7C-5W-5Mo-5V-10Cr-2.5Ti were invented with the additions of 1.6wt%B and 2.7wt%B.The aim of this work was to study the effect of boron on the structural state of the alloys and phase elemental distribution with respect to the formation of wear-resistant structural constituents.It was found that the alloy containing 1.6wt%B was composed of three eutectics:(a)“M_(2)(C,B)_(5)+ferrite”having a“Chinese Script”morphology(89.8vol%),(b)“M_(7)(C,B)_(3)+Austenite”having a“Rosette”morphology,and(c)“M_(3)C+Austenite”having a“Ledeburite”-shaped morphology(2.7vol%).With 2.7wt%of boron content,the bulk hardness increased from HRC 31 to HRC 38.5.The primary carboborides M_(2)(C,B)_(5) with average microhardness of HV 2797 appeared in the structure with a volume fraction of 17.6vol%.The volume fraction of eutectics(a)and(b,c)decreased to 71.2vol%and 3.9vol%,respectively.The matrix was“ferrite/austenite”for 1.6wt%B and“ferrite/pearlite”for 2.7wt%B.Both cast irons contained compact precipitates of carbide(Ti,M)C and carboboride(Ti,M)(C,В)with a volume fraction of 7.3%-7.5%.Based on the energy-dispersive X-ray spectroscopy,the elemental phase distributions and the appropriate phase formulas are presented in this work.展开更多
基金supported by the Ministry of Education and Science of Ukraine(No.0123U101834)support in the framework of the“EU Next generation EU through the Recovery and Resilience Plan for Slovakia”(Nos.09I03-03-V01-00061 and 09I03-03-V01-00099)。
文摘Wrought and laser powder bed fusion(LPBF)Ti−6Al−4V(Ti-6-4)specimens were comparatively evaluated,with the objective to determine LPBF Ti−6Al−4V’s suitability for biomedical applications.Testing included nanoindentation,cyclic polarization in simulated body fluid(SBF,37°C),and dry and SBF“ball-on-plate”sliding.Wrought Ti-6-4 exhibited a lamellarα+βmicrostructure,whereas LPBF Ti-6-4 displayed a fine-grainedα′-martensite microstructure.LPBF Ti-6-4 demonstrated~3%higher indentation modulus and~32%higher hardness,while wrought Ti-6-4 showed~8%higher plasticity.Both alloys exhibited low corrosion rates(10−5 mA/cm^(2)order)and true passivity(10−4 mA/cm^(2)order).No localized corrosion was observed in either two alloys,except for occasional metastable pitting in the LPBF alloy.However,LPBF Ti-6-4 presented higher corrosion rate and passive current,ascribed to its martensitic structure.During dry sliding,LPBF Ti-6-4 exhibited~14%lower volume loss compared to wrought Ti-6-4.Sliding in SBF increased volume losses for both alloys,with wear resistances nearly equalized,as the advantage of LPBF Ti-6-4 decreased due to more intense wear-accelerated corrosion induced by the stressed martensite.Overall,the results demonstrate the suitability of LPBF Ti-6-4 for biomedical uses.
基金This work was financially supported by Ministry of Edu-cation and Science of Ukraine under the project No 0119U100080.
文摘The novel cast irons of chemical composition(wt%)0.7C-5W-5Mo-5V-10Cr-2.5Ti were invented with the additions of 1.6wt%B and 2.7wt%B.The aim of this work was to study the effect of boron on the structural state of the alloys and phase elemental distribution with respect to the formation of wear-resistant structural constituents.It was found that the alloy containing 1.6wt%B was composed of three eutectics:(a)“M_(2)(C,B)_(5)+ferrite”having a“Chinese Script”morphology(89.8vol%),(b)“M_(7)(C,B)_(3)+Austenite”having a“Rosette”morphology,and(c)“M_(3)C+Austenite”having a“Ledeburite”-shaped morphology(2.7vol%).With 2.7wt%of boron content,the bulk hardness increased from HRC 31 to HRC 38.5.The primary carboborides M_(2)(C,B)_(5) with average microhardness of HV 2797 appeared in the structure with a volume fraction of 17.6vol%.The volume fraction of eutectics(a)and(b,c)decreased to 71.2vol%and 3.9vol%,respectively.The matrix was“ferrite/austenite”for 1.6wt%B and“ferrite/pearlite”for 2.7wt%B.Both cast irons contained compact precipitates of carbide(Ti,M)C and carboboride(Ti,M)(C,В)with a volume fraction of 7.3%-7.5%.Based on the energy-dispersive X-ray spectroscopy,the elemental phase distributions and the appropriate phase formulas are presented in this work.
