The effects of minor Sc and Zr additions on the mechanical properties and microstructure evolution of Al Zn Mg Cu alloys were studied using tensile tests, scanning electron microscopy (SEM) and transmission electron m...The effects of minor Sc and Zr additions on the mechanical properties and microstructure evolution of Al Zn Mg Cu alloys were studied using tensile tests, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The ultimate tensile strength of the peak-aged Al Zn Mg Cu alloy is improved by about 105 MPa with the addition of 0.10% Zr. An increase of about 133 MPa is observed with the joint addition of 0.07% Sc and 0.07% Zr. For the alloys modified with the minor addition of Sc and Zr (0.14%), the main strengthening mechanisms of minor addition of Sc and Zr are fine-grain strengthening, sub-structure strengthening and the Orowan strengthening mechanism produced by the Al3(Sc,Zr) and Al3Zr dispersoids. The volume of Al3Zr particles is less than that of Al3(Sc,Zr) particles, but the distribution of Al3(Sc,Zr) particles is more dispersed throughout the matrix leading to pinning the dislocations motion and restraining the recrystallization more effectively.展开更多
Eight new polycyclic phloroglucinol meroterpenoids guajamers A-H(1-8),a methylated benzoylphloroglucinol meroterpenoid guajamer I(9)representing a new skeleton,and two known analogues(10 and 11)were isolated from the ...Eight new polycyclic phloroglucinol meroterpenoids guajamers A-H(1-8),a methylated benzoylphloroglucinol meroterpenoid guajamer I(9)representing a new skeleton,and two known analogues(10 and 11)were isolated from the leaves of Psidium guajava.The structures of new molecules were elucidated by detailed analysis of spectroscopic data,and those of 1,2,8,and 9 were unambiguously confirmed by single-crystal X-ray diffraction study.Structurally,compounds 1-8 were sesquiterpene and monoterpene-based meroterpenoids with rearranged skeletons,while compound 9 was the first case of 3-alkyl-5-formyl-benzoylphloroglucinol-coupled sesquiterpene containing an unusual C-l-spiro-fused 6/6/9/4 polycyclic skeleton.In addition,all the isolated compounds were evaluated for their antibacterial activity against three bacterial strains,and most of them(compounds 2-7,10,and 11)showed antibacterial activity against Staphylococcus aureus and Staphylococcus epidermidis with MIC values of 8-32 μmol/L.These findings suggested that meroterpenoids isolated from Psidium guajava can be considered as potential antibacterial leading compounds for pharmaceutical industry.展开更多
基金financially supported by the Natural Science Foundation of Hunan Province(Nos.2020JJ4114,2016JJ3151)the National Natural Science Foundation of China(No.51601229)+2 种基金the Young Elite Scientist Sponsorship Program by CAST(No.2015QNRC001)the Hunan Province Innovation Platform and Talent Plan Project,China(No.2015RS4001)the Open-End Fund for the Valuable and Precision Instruments of Central South University,China(No.CSUZC201815)。
文摘采用选择激光熔化(SLM)技术在不同工艺参数下制备Al-4.77Mn-1.37Mg-0.67Sc-0.25Zr合金(质量分数,%),通过拉伸试验和显微观察研究合金的组织和力学性能。结果表明:当能量密度为104~143 J/mm^(3)时,力学性能保持相对稳定;屈服强度为335~338 MPa,抗拉强度为397~400 MPa,伸长率均在11%以上。在此能量密度区间内,SLM合金缺陷和粗大金属间化合物较少,与此同时,有大量细小的Al Fe Mn Sc Zr相析出。当能量密度超过152 J/mm^(3)时,可以观察到一些孔洞和裂纹,且伸长率急剧下降。定量计算结果表明,该合金固溶强化、晶界强化和析出强化占比分别为44%、41%和15%。
基金Project (2016B090931004) supported by the Scientific and Research Plan of Guangdong Province, ChinaProject (51601229) supported by the National Natural Science Foundation of China。
文摘The effects of minor Sc and Zr additions on the mechanical properties and microstructure evolution of Al Zn Mg Cu alloys were studied using tensile tests, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The ultimate tensile strength of the peak-aged Al Zn Mg Cu alloy is improved by about 105 MPa with the addition of 0.10% Zr. An increase of about 133 MPa is observed with the joint addition of 0.07% Sc and 0.07% Zr. For the alloys modified with the minor addition of Sc and Zr (0.14%), the main strengthening mechanisms of minor addition of Sc and Zr are fine-grain strengthening, sub-structure strengthening and the Orowan strengthening mechanism produced by the Al3(Sc,Zr) and Al3Zr dispersoids. The volume of Al3Zr particles is less than that of Al3(Sc,Zr) particles, but the distribution of Al3(Sc,Zr) particles is more dispersed throughout the matrix leading to pinning the dislocations motion and restraining the recrystallization more effectively.
基金the National Natural Science Foundation of China(No.21772234)the National New Drug Innovation Major Project of China(Nos.2018ZX09735006,2018ZX09711001-001,and 2018ZX09711001-002-010)the independent project of State Key Laboratory of Bioactive Substance and Function of Natural Medicines(No.GTZA201803).
文摘Eight new polycyclic phloroglucinol meroterpenoids guajamers A-H(1-8),a methylated benzoylphloroglucinol meroterpenoid guajamer I(9)representing a new skeleton,and two known analogues(10 and 11)were isolated from the leaves of Psidium guajava.The structures of new molecules were elucidated by detailed analysis of spectroscopic data,and those of 1,2,8,and 9 were unambiguously confirmed by single-crystal X-ray diffraction study.Structurally,compounds 1-8 were sesquiterpene and monoterpene-based meroterpenoids with rearranged skeletons,while compound 9 was the first case of 3-alkyl-5-formyl-benzoylphloroglucinol-coupled sesquiterpene containing an unusual C-l-spiro-fused 6/6/9/4 polycyclic skeleton.In addition,all the isolated compounds were evaluated for their antibacterial activity against three bacterial strains,and most of them(compounds 2-7,10,and 11)showed antibacterial activity against Staphylococcus aureus and Staphylococcus epidermidis with MIC values of 8-32 μmol/L.These findings suggested that meroterpenoids isolated from Psidium guajava can be considered as potential antibacterial leading compounds for pharmaceutical industry.
