The construction and application of traditional high-strength 7075 aluminum alloy(Al7075) through selective laser melting(SLM) are currently restricted by the serious hot cracking phenomenon. To address this critical ...The construction and application of traditional high-strength 7075 aluminum alloy(Al7075) through selective laser melting(SLM) are currently restricted by the serious hot cracking phenomenon. To address this critical issue, in this study, Si is employed to assist the SLM printing of high-strength Al7075. The laser energy density during SLM is optimized, and the eff ects of Si element on solidification path, relative density, microstructure and mechanical properties of Al7075 alloy are studied systematically. With the modified solidification path, laser energy density, and the dense microstructure with refined grain size and semi-continuous precipitates network at grain boundaries, which consists of fine Si, β-MgSi, Q-phase and θ-AlCu, the hot cracking phenomenon and mechanical properties are eff ectively improved. As a result, the tensile strength of the SLM-processed Si-modified Al7075 can reach 486 ± 3 MPa, with a high relative density of ~ 99.4%, a yield strength of 291 ± 8 MPa, fracture elongation of(6.4 ± 0.4)% and hardness of 162 ± 2(HV) at the laser energy density of 112.5 J/mm~3. The main strengthening mechanism with Si modification is demonstrated to be the synergetic enhancement of grain refinement, solution strengthening, load transfer, and dislocation strengthening. This work will inspire more new design of high-strength alloys through SLM.展开更多
Carbon-supported single-atom catalysts(C-SACs)have been demonstrated as a strategy to promote the reversible conversion reaction of metal sulfide anodes in sodium-ion batteries(SIBs).However,the design principle of pr...Carbon-supported single-atom catalysts(C-SACs)have been demonstrated as a strategy to promote the reversible conversion reaction of metal sulfide anodes in sodium-ion batteries(SIBs).However,the design principle of promising C-SACs remains lacking for obtaining highly reversible metal sulfide anodes.We designed a phosphorus-doped carbon-supported single-atom Mn catalyst(PC-SAMn)with an asymmetrical dual active center.The sulfiphilic Mn and sodiophilic P active centers adsorb discharged Na 2S through Mn-S d-p and P-Na s-p orbital hybridizations.The asymmetrical dual active center induced the asymmetrical adsorption configuration of Na 2S,which efficiently weakened Na-S bond strength and facilitated the decomposition of Na 2S during charging.As a result,the designed catalyst enables typical MoS_(2) with a record-high compositional reversible degree of 89.61%and a low capacity decay ratio of only 0.18%per 100 cycles during 2000 cycles.The research establishes the“orbital hybridization-molecular structure-catalytic activity”relationship for guiding the design of highly reversible conversion-type materials.展开更多
基金financially supported by the Joint Fund Project of Equipment Pre-research of Education Ministry(Grant No.6141A02033230)。
文摘The construction and application of traditional high-strength 7075 aluminum alloy(Al7075) through selective laser melting(SLM) are currently restricted by the serious hot cracking phenomenon. To address this critical issue, in this study, Si is employed to assist the SLM printing of high-strength Al7075. The laser energy density during SLM is optimized, and the eff ects of Si element on solidification path, relative density, microstructure and mechanical properties of Al7075 alloy are studied systematically. With the modified solidification path, laser energy density, and the dense microstructure with refined grain size and semi-continuous precipitates network at grain boundaries, which consists of fine Si, β-MgSi, Q-phase and θ-AlCu, the hot cracking phenomenon and mechanical properties are eff ectively improved. As a result, the tensile strength of the SLM-processed Si-modified Al7075 can reach 486 ± 3 MPa, with a high relative density of ~ 99.4%, a yield strength of 291 ± 8 MPa, fracture elongation of(6.4 ± 0.4)% and hardness of 162 ± 2(HV) at the laser energy density of 112.5 J/mm~3. The main strengthening mechanism with Si modification is demonstrated to be the synergetic enhancement of grain refinement, solution strengthening, load transfer, and dislocation strengthening. This work will inspire more new design of high-strength alloys through SLM.
基金supported by the Young Elite Scientists Sponsorship Program by China Association for Science and Technology(2022QNRC001)the Natural Science Foundation of Tianjin City(23JCZDJC01110)+5 种基金the National Natural Science Foundation of China(51972225 and 52202281)the Tianjin University Science and Technology Innovation Leading Talent Training Programthe Natural Science Foundation of Chongqing(CSTB2023NSCQ-MSX0538)the Natural Science Basic Research Program of Shaanxi(2024JC-YBQN-0073)the Young Talent Fund of Association for Science and Technology in Shaanxi(20230101)the Innovation Capability Support Program of Shaanxi-Science and Technology Innovation Team Project(2025RS-CXTD-024)。
文摘Carbon-supported single-atom catalysts(C-SACs)have been demonstrated as a strategy to promote the reversible conversion reaction of metal sulfide anodes in sodium-ion batteries(SIBs).However,the design principle of promising C-SACs remains lacking for obtaining highly reversible metal sulfide anodes.We designed a phosphorus-doped carbon-supported single-atom Mn catalyst(PC-SAMn)with an asymmetrical dual active center.The sulfiphilic Mn and sodiophilic P active centers adsorb discharged Na 2S through Mn-S d-p and P-Na s-p orbital hybridizations.The asymmetrical dual active center induced the asymmetrical adsorption configuration of Na 2S,which efficiently weakened Na-S bond strength and facilitated the decomposition of Na 2S during charging.As a result,the designed catalyst enables typical MoS_(2) with a record-high compositional reversible degree of 89.61%and a low capacity decay ratio of only 0.18%per 100 cycles during 2000 cycles.The research establishes the“orbital hybridization-molecular structure-catalytic activity”relationship for guiding the design of highly reversible conversion-type materials.
