The excellent shape memory and mechanical properties of Ti Ni shape memory alloys(SMAs) fabricated using selective laser melting(SLM) are highly desirable for a wide range of critical applications. In this study, we e...The excellent shape memory and mechanical properties of Ti Ni shape memory alloys(SMAs) fabricated using selective laser melting(SLM) are highly desirable for a wide range of critical applications. In this study, we examined the simultaneous enhancement of mechanical and shape memory properties using heat-treatment homogenization of Ti_(2)Ni precipitates in a Ti_(50.6)Ni_(49.4)SMA fabricated using SLM. Specifically, because of the complete solution treatment, nanoscale spherical Ti_(2)Ni precipitates were homogeneously dispersed throughout the grain interior. Interestingly, the resultant SMA exhibited an ultrahigh tensile strength of 880 ± 13 MPa, a large elongation of 22.4 ± 0.4%, and an excellent shape memory effect, with a recovery rate of > 98% and ultrahigh recoverable strain of 5.32% after ten loading–unloading cycles. These simultaneously enhanced properties are considerably superior than those of most previously reported Ti Ni SMAs fabricated using additive manufacturing. Fundamentally, the enhancement in tensile strength is ascribed to precipitation strengthening and work hardening, and the large plasticity is mainly attributed to the homogeneous nanoscale globular Ti_(2)Ni precipitates, which effectively impeded the rapid propagation of microcracks. Furthermore, the enhanced shape memory properties are derived from the suppression of dislocation movement and formation of retained stabilized martensite by the presence of high-density dislocations, nanoscale Ti_(2)Ni precipitates, and abundant interfaces. The obtained results provide insight into the enhancement of the two types of properties in Ti Ni SMAs and will accelerate the wider application of SMAs.展开更多
A pot experiment was conducted in a plastic film house to evaluate the translocation and uptake of heavy metals(Pb,Cd,Cu,and Zn) into brown rice(Oryza sativa L.) and the heavy metals residues in soils which had previo...A pot experiment was conducted in a plastic film house to evaluate the translocation and uptake of heavy metals(Pb,Cd,Cu,and Zn) into brown rice(Oryza sativa L.) and the heavy metals residues in soils which had previously been irrigated with domestic wastewater for a long time(3 years).The range of Pb,Cd,Cu,and Zn was 5.10 ± 0.01,0.105 ± 0.017,5.76 ± 0.42,and 23.56 ± 1.40 mg kg-1,respectively in the domestic wastewater-irrigated soil,and 0.370 ± 0.006,0.011 ± 0.001,0.340 ± 0.04,and 2.05 ± 0.18 mg kg-1,respectively,in the domestic wastewater-irrigated brown rice.The results indicated that application of domestic wastewater to arable land slightly increased the levels of Pb,Cd,Cu,and Zn in soil and brown rice(P < 0.01).The concentrations of heavy metals in brown rice were lower than the recommended tolerable levels proposed by the Joint FAO/WHO Expert Committee on Food Additives.However,the continuous monitoring and pollution control of hazardous materials from domestic wastewater are needed in order to prevent excessive build-up of heavy metals in the food chain.展开更多
The Ti-6Al-4V alloy is the most widely utilized titanium metal alloy globally,making the enhancement of its mechanical properties important.In this study,we achieved an ultimate tensile strength of 1.5 GPa through the...The Ti-6Al-4V alloy is the most widely utilized titanium metal alloy globally,making the enhancement of its mechanical properties important.In this study,we achieved an ultimate tensile strength of 1.5 GPa through the additive manufacturing(AM)of Ti-6Al-4V.Specifically,the Ti-6Al-4V alloy was fabricated via laser powder bed fusion(L-PBF)using Ti-6Al-4V powder subjected to cold plastic deformation(CPD Ti-6Al-4V).The microstructural evolution of the Ti-6Al-4V powder during CPD was analyzed in detail.The CPD Ti-6Al-4V powder exhibited a core-shell structure with subgrains and nanocrystals formed via high-density dislocations within the shell.In addition,the as-printed CPD Ti-6Al-4V alloy had an average grain size of approximately 1.9µm.The presence of interstitial elements and finer grains resulted in the formation of Ti-6Al-4V alloys with ultrahigh strengths(ultimate tensile strength of approximately 1500 MPa,yield strength of 1320 MPa,and elongation of 6%).This groundbreaking achievement paves the way for further advancements in AM technology and presents exciting opportunities for innovation across a range of high-strength materials,which are crucial for achieving optimal performance.展开更多
基金supported financially by the Key-Area Research and Development Program of Guangdong Province (No. 2020B090923001)the National Natural Science Foundation of China (No. U19A2085)+3 种基金the Key Basic and Applied Research Program of Guangdong Province (No. 2019B030302010)the financial support from the China Postdoctoral Science Foundation (No. 2019M662908)Guangdong Basic and Applied Basic Research Foundation (No.2019A1515110215)the Fundamental Research Funds for the Central Universities (No.2020ZYGXZR030)。
文摘The excellent shape memory and mechanical properties of Ti Ni shape memory alloys(SMAs) fabricated using selective laser melting(SLM) are highly desirable for a wide range of critical applications. In this study, we examined the simultaneous enhancement of mechanical and shape memory properties using heat-treatment homogenization of Ti_(2)Ni precipitates in a Ti_(50.6)Ni_(49.4)SMA fabricated using SLM. Specifically, because of the complete solution treatment, nanoscale spherical Ti_(2)Ni precipitates were homogeneously dispersed throughout the grain interior. Interestingly, the resultant SMA exhibited an ultrahigh tensile strength of 880 ± 13 MPa, a large elongation of 22.4 ± 0.4%, and an excellent shape memory effect, with a recovery rate of > 98% and ultrahigh recoverable strain of 5.32% after ten loading–unloading cycles. These simultaneously enhanced properties are considerably superior than those of most previously reported Ti Ni SMAs fabricated using additive manufacturing. Fundamentally, the enhancement in tensile strength is ascribed to precipitation strengthening and work hardening, and the large plasticity is mainly attributed to the homogeneous nanoscale globular Ti_(2)Ni precipitates, which effectively impeded the rapid propagation of microcracks. Furthermore, the enhanced shape memory properties are derived from the suppression of dislocation movement and formation of retained stabilized martensite by the presence of high-density dislocations, nanoscale Ti_(2)Ni precipitates, and abundant interfaces. The obtained results provide insight into the enhancement of the two types of properties in Ti Ni SMAs and will accelerate the wider application of SMAs.
文摘A pot experiment was conducted in a plastic film house to evaluate the translocation and uptake of heavy metals(Pb,Cd,Cu,and Zn) into brown rice(Oryza sativa L.) and the heavy metals residues in soils which had previously been irrigated with domestic wastewater for a long time(3 years).The range of Pb,Cd,Cu,and Zn was 5.10 ± 0.01,0.105 ± 0.017,5.76 ± 0.42,and 23.56 ± 1.40 mg kg-1,respectively in the domestic wastewater-irrigated soil,and 0.370 ± 0.006,0.011 ± 0.001,0.340 ± 0.04,and 2.05 ± 0.18 mg kg-1,respectively,in the domestic wastewater-irrigated brown rice.The results indicated that application of domestic wastewater to arable land slightly increased the levels of Pb,Cd,Cu,and Zn in soil and brown rice(P < 0.01).The concentrations of heavy metals in brown rice were lower than the recommended tolerable levels proposed by the Joint FAO/WHO Expert Committee on Food Additives.However,the continuous monitoring and pollution control of hazardous materials from domestic wastewater are needed in order to prevent excessive build-up of heavy metals in the food chain.
基金supported by the Guangdong Basic and Applied Basic Research Foundation(No.2020B1515120013)the National Natural Science Foundation of China(Nos.51971108 and 52271032)+1 种基金the Key Research and Development Program of Jiangsu Province(No.K22251901)the Shenzhen Science and Technology Innovation Commission(Nos.JCYJ20220818100612027 and JSGG20210420091802007).
文摘The Ti-6Al-4V alloy is the most widely utilized titanium metal alloy globally,making the enhancement of its mechanical properties important.In this study,we achieved an ultimate tensile strength of 1.5 GPa through the additive manufacturing(AM)of Ti-6Al-4V.Specifically,the Ti-6Al-4V alloy was fabricated via laser powder bed fusion(L-PBF)using Ti-6Al-4V powder subjected to cold plastic deformation(CPD Ti-6Al-4V).The microstructural evolution of the Ti-6Al-4V powder during CPD was analyzed in detail.The CPD Ti-6Al-4V powder exhibited a core-shell structure with subgrains and nanocrystals formed via high-density dislocations within the shell.In addition,the as-printed CPD Ti-6Al-4V alloy had an average grain size of approximately 1.9µm.The presence of interstitial elements and finer grains resulted in the formation of Ti-6Al-4V alloys with ultrahigh strengths(ultimate tensile strength of approximately 1500 MPa,yield strength of 1320 MPa,and elongation of 6%).This groundbreaking achievement paves the way for further advancements in AM technology and presents exciting opportunities for innovation across a range of high-strength materials,which are crucial for achieving optimal performance.
