The expanding of material library of laser powder bed fusion(L-PBF)is of great significance to the development of material science.In this study,the biomedical Ti-13Nb-13Zr powder was mixed with the tantalum particles...The expanding of material library of laser powder bed fusion(L-PBF)is of great significance to the development of material science.In this study,the biomedical Ti-13Nb-13Zr powder was mixed with the tantalum particles(2 wt%−8 wt%)and fabricated by L-PBF.The microstructure consists of aβmatrix with partially unmelted pure tantalum distributed along the boundaries of molten pool owing to the Marangoni convention.Because the melting process of Ta absorbs lots of energy,the size of molten pool becomes smaller with the increase of Ta content.The fine microstructure exists in the center of melt pool while coarse microstructure is on the boundaries of melt pool because of the existence of heat-affected zone.The columnar-to-equiaxed transitions(CETs)happen in the zones near the unmelted Ta,and the low lattice mismatch induced by solid Ta phase is responsible for this phenomenon.The recrystallization texture is strengthened while the fiber texture is weakened when the tantalum content is increased.Due to the formation of refined martensiteα′grains during L-PBF,the compressive strengths of L-PBF-processed samples are higher than those fabricated by traditional processing technologies.The present research will provide an important reference for biomedical alloy design via L-PBF process in the future.展开更多
With the experiment and finite element simulation, the influences of power ultrasonic on the solidification structure of 7050 aluminum alloy ingot in semi-continuous casting were researched, and the effects of casting...With the experiment and finite element simulation, the influences of power ultrasonic on the solidification structure of 7050 aluminum alloy ingot in semi-continuous casting were researched, and the effects of casting speed on solidification structure in ultrasonic field were also analyzed. The experiment and simulation results show that the solidification structure of the ingot is homogeneously distributed, and its grain size is obviously refined at ultrasonic power of 240 W. The average grain sizes, which can be seen from the Leica microscope, are less than 100 μm. When the casting speed is 45-50 mm/min, the best grain refinement is obtained.展开更多
The solidification microstructure,fracture morphologies,and mechanical properties of an Al-18Si alloy and alloys modified with Al-5Ti and Al-3P master alloys were investigated using an optical microscope,scanning elec...The solidification microstructure,fracture morphologies,and mechanical properties of an Al-18Si alloy and alloys modified with Al-5Ti and Al-3P master alloys were investigated using an optical microscope,scanning electron microscope,and an electronic universal testing machine.The results show that additions of Al-5Ti and Al-3P have significant effects on the size and area fraction of the primary Si and the mechanical properties of the Al-18Si alloy.Compared to the Al-18Si alloy modified with 0.6 wt%Al-5Ti at 850°C,when the Al-18Si alloy was modified with 0.3 wt%Al-5Ti and 0.5 wt%Al-3P at the same temperature,the average size of the primary Si decreased from 39 to 14μm and the area fraction increased from 9.5%to 11.6%.The biggest influencing factor on the tensile strength and elongation of the Al-18Si alloy is the addition of Al-3P,followed by the modification temperature and the addition of Al-5Ti.At a modification temperature of 850°C,the tensile strength and elongation of the Al-18Si alloy modified with 0.3 wt%Al-5Ti+0.5 wt%Al-3P increased by 19.6%and 88.6%,respectively compared to that of the Al-18Si alloy modified with 0.6 wt%Al-5Ti.展开更多
基金Projects(51975061,51775055)supported by the National Natural Science Foundation of ChinaProject(2020JJ5599)supported by the Natural Science Foundation of Hunan Province,ChinaProjects(19C0032,19B033)supported by the Research Foundation of Education Bureau of Hunan Province,China。
文摘The expanding of material library of laser powder bed fusion(L-PBF)is of great significance to the development of material science.In this study,the biomedical Ti-13Nb-13Zr powder was mixed with the tantalum particles(2 wt%−8 wt%)and fabricated by L-PBF.The microstructure consists of aβmatrix with partially unmelted pure tantalum distributed along the boundaries of molten pool owing to the Marangoni convention.Because the melting process of Ta absorbs lots of energy,the size of molten pool becomes smaller with the increase of Ta content.The fine microstructure exists in the center of melt pool while coarse microstructure is on the boundaries of melt pool because of the existence of heat-affected zone.The columnar-to-equiaxed transitions(CETs)happen in the zones near the unmelted Ta,and the low lattice mismatch induced by solid Ta phase is responsible for this phenomenon.The recrystallization texture is strengthened while the fiber texture is weakened when the tantalum content is increased.Due to the formation of refined martensiteα′grains during L-PBF,the compressive strengths of L-PBF-processed samples are higher than those fabricated by traditional processing technologies.The present research will provide an important reference for biomedical alloy design via L-PBF process in the future.
基金Project(2010CB731700) supported by the National Basic Research Program of China
文摘With the experiment and finite element simulation, the influences of power ultrasonic on the solidification structure of 7050 aluminum alloy ingot in semi-continuous casting were researched, and the effects of casting speed on solidification structure in ultrasonic field were also analyzed. The experiment and simulation results show that the solidification structure of the ingot is homogeneously distributed, and its grain size is obviously refined at ultrasonic power of 240 W. The average grain sizes, which can be seen from the Leica microscope, are less than 100 μm. When the casting speed is 45-50 mm/min, the best grain refinement is obtained.
基金Project(51571039) supported by the National Natural Science Foundation of China
文摘The solidification microstructure,fracture morphologies,and mechanical properties of an Al-18Si alloy and alloys modified with Al-5Ti and Al-3P master alloys were investigated using an optical microscope,scanning electron microscope,and an electronic universal testing machine.The results show that additions of Al-5Ti and Al-3P have significant effects on the size and area fraction of the primary Si and the mechanical properties of the Al-18Si alloy.Compared to the Al-18Si alloy modified with 0.6 wt%Al-5Ti at 850°C,when the Al-18Si alloy was modified with 0.3 wt%Al-5Ti and 0.5 wt%Al-3P at the same temperature,the average size of the primary Si decreased from 39 to 14μm and the area fraction increased from 9.5%to 11.6%.The biggest influencing factor on the tensile strength and elongation of the Al-18Si alloy is the addition of Al-3P,followed by the modification temperature and the addition of Al-5Ti.At a modification temperature of 850°C,the tensile strength and elongation of the Al-18Si alloy modified with 0.3 wt%Al-5Ti+0.5 wt%Al-3P increased by 19.6%and 88.6%,respectively compared to that of the Al-18Si alloy modified with 0.6 wt%Al-5Ti.
