Replication processing using NaCl spaceholders offers the possibility to produce cellular structures for a range of Mg alloys. Four Mg alloys (AZ63, M2, ZM21 and MZX211) were processed into open cellular structures wi...Replication processing using NaCl spaceholders offers the possibility to produce cellular structures for a range of Mg alloys. Four Mg alloys (AZ63, M2, ZM21 and MZX211) were processed into open cellular structures with a pore size near 500 μm and a porosity of 75% using an optimized NaCl leaching procedure. The production method was found to be robust and yielded samples of acceptable strength and stiffness. Their dissolution rate (by H2 release in simulated body fluid) and mechanical properties (by cyclic compression) were measured. For all 4 alloys the initial mechanical properties mimic those of cancellous bone;however, the dissolution rate is too high for direct use in the human body, leading to excessive hydrogen evolution and overly rapid degradation of mechanical properties. Further post-processing of the material is thus required.展开更多
In this work,NiTi samples with different thicknesses(0.15-1.00 mm)were fabricated by laser powder bed fusion(LPBF)under variable scanning speeds(500-1200 mm s^(-1)).The densification behavior,phase transformation beha...In this work,NiTi samples with different thicknesses(0.15-1.00 mm)were fabricated by laser powder bed fusion(LPBF)under variable scanning speeds(500-1200 mm s^(-1)).The densification behavior,phase transformation behavior,and mechanical properties of the sample with different thicknesses are studied.The results indicate a strong size effect in the LPBF-fabricated NiTi alloy.The decrease of the sample thickness results in(i)the increase of porosity,(ii)the decrease of the number of adhered NiTi powder particles at the surface,(iii)the monotonous decrease of the martensitic transformation temperatures(MTTs),and(iv)the decrease of the shape recovery temperature.The influence of sample thickness on the melt-pool behavior,and thus the microstructure and performance of NiTi alloys are discussed.It is suggested that the melt-pool is deeper and narrower in the thin samples than in the thick samples.We conclude that,apart from the LPBF process conditions,the sample dimensions have also to be considered to fabricate NiTi structures with predictable properties.展开更多
基金This work has been funded by core funding of the Department of Metallurgy and Materials Engineering at KU Leuven and the Laboratory of Mechanical Metallurgy at EPFL.
文摘Replication processing using NaCl spaceholders offers the possibility to produce cellular structures for a range of Mg alloys. Four Mg alloys (AZ63, M2, ZM21 and MZX211) were processed into open cellular structures with a pore size near 500 μm and a porosity of 75% using an optimized NaCl leaching procedure. The production method was found to be robust and yielded samples of acceptable strength and stiffness. Their dissolution rate (by H2 release in simulated body fluid) and mechanical properties (by cyclic compression) were measured. For all 4 alloys the initial mechanical properties mimic those of cancellous bone;however, the dissolution rate is too high for direct use in the human body, leading to excessive hydrogen evolution and overly rapid degradation of mechanical properties. Further post-processing of the material is thus required.
基金supported by the National Nature Science Foun-dation of China(grant No.51905310)Natural Science Founda-tion of Shandong Province(Nos.ZR2020YQ39 and ZR2020ZD05)+2 种基金the Young Scholars Program of Shandong University(grant No.2018WLJH24)and Shandong Medical Products Administration(grant No.SDNMPAFZLX202204)the sup-port from MCIN/AEI/10.13039/501100011033 and FEDER Una Man-era de Hacer Europa,EU(project No.RTI2018-094683-B-C51).
文摘In this work,NiTi samples with different thicknesses(0.15-1.00 mm)were fabricated by laser powder bed fusion(LPBF)under variable scanning speeds(500-1200 mm s^(-1)).The densification behavior,phase transformation behavior,and mechanical properties of the sample with different thicknesses are studied.The results indicate a strong size effect in the LPBF-fabricated NiTi alloy.The decrease of the sample thickness results in(i)the increase of porosity,(ii)the decrease of the number of adhered NiTi powder particles at the surface,(iii)the monotonous decrease of the martensitic transformation temperatures(MTTs),and(iv)the decrease of the shape recovery temperature.The influence of sample thickness on the melt-pool behavior,and thus the microstructure and performance of NiTi alloys are discussed.It is suggested that the melt-pool is deeper and narrower in the thin samples than in the thick samples.We conclude that,apart from the LPBF process conditions,the sample dimensions have also to be considered to fabricate NiTi structures with predictable properties.
