Mg−1Mn−0.5Al−0.5Ca−0.5Zn(wt.%)alloy was fabricated by conventional extrusion at 673 K with an extrusion ratio of 25:1,followed by aging at 473 K.The microstructure was characterized by scanning electron microscopy,ele...Mg−1Mn−0.5Al−0.5Ca−0.5Zn(wt.%)alloy was fabricated by conventional extrusion at 673 K with an extrusion ratio of 25:1,followed by aging at 473 K.The microstructure was characterized by scanning electron microscopy,electron back-scattered diffraction,and transmission electron microscopy.The mechanical properties were determined by the tensile test.The peak-aged sample shows fine recrystallized grains with an average grain size of 1.7μm.Area fraction of Al−Ca particles in the alloy increases significantly after peak aging.Meanwhile,botháañandác+añdislocations were observed to remain in the alloy after hot extrusion.Thus,the peak-aged sample exhibits simultaneously high strength and good ductility with the ultimate tensile stress,tensile yield stress,and tension fracture elongation of 320 MPa,314 MPa,and 19.0%,respectively.展开更多
The Gibbs free energy and critical reaction conditions of preparing Mg and Ca metal by carbothermic reducing calcined dolomite were calculated and analyzed.New thermodynamic criterion for reduction reaction,including ...The Gibbs free energy and critical reaction conditions of preparing Mg and Ca metal by carbothermic reducing calcined dolomite were calculated and analyzed.New thermodynamic criterion for reduction reaction,including the critical temperature and vacuum degree,was studied.The results show that:when T/P^(0.0449)<1199.2,neither MgO nor CaO can be reduced by carbon;when T/P^(0.0449)≥1199.2 and T/P^(0.0462)<1350.9,MgO can be reduced while CaO can not be;when T/P^(0.0462)≥1350.9,both MgO and CaO can be reduced.According to the requirements,we can obtain only Mg,Mg first then Ca,Mg and Ca simultaneously by controlling temperature,vacuum degree or both of them properly,by carbothermic reducing calcined dolomite.展开更多
The as-rolled AZ31 Mg alloy sheets are welded by friction stir welding(FSW) in this study, followed by annealing and hot rolling with different reductions. The effects of welding speed and the rolling reduction on t...The as-rolled AZ31 Mg alloy sheets are welded by friction stir welding(FSW) in this study, followed by annealing and hot rolling with different reductions. The effects of welding speed and the rolling reduction on the microstructure, tensile properties, microhardness and fracture surfaces of the specimens are investigated. The results show that the microstructures of the FSW joint in different regions become more and more consistent as the hot rolling reduction increases. The mechanical properties of the FSW joints and the joint coefficient are improved with increasing rolling reduction; however,the hardness value in the stirred zone decreases firstly and then increases. When the rolling reduction is 50%, the tensile strength of FSW joint is close to that of base metal. The sample L_3 achieves the best comprehensive properties, with the yield strength, ultimate tensile strength and elongation of 162, 287.9 MPa, and 17.9%, respectively.展开更多
Dear Editor,The epithelial-to-mesenchymal transition(EMT)is a positive modulator of triple-negative breast cancer(TNBC)progression.1 Several EMT-inducing transcriptional factors(EMT-TFs)drive EMT process and enhance T...Dear Editor,The epithelial-to-mesenchymal transition(EMT)is a positive modulator of triple-negative breast cancer(TNBC)progression.1 Several EMT-inducing transcriptional factors(EMT-TFs)drive EMT process and enhance TNBC progression.2 Promoting the degradation of EMT-TFs to inhibit EMT and malignant actions holds therapeutic potential for TNBC patients.展开更多
Mg–9Li–3Al–1.6Y alloys were prepared through mixture method. The microstructure, mechanical properties, and corrosion resistance of the as-cast and asextruded alloys were studied by optical microscopy(OM),scannin...Mg–9Li–3Al–1.6Y alloys were prepared through mixture method. The microstructure, mechanical properties, and corrosion resistance of the as-cast and asextruded alloys were studied by optical microscopy(OM),scanning electronic microscopy(SEM), X-ray diffraction(XRD), mechanical properties testing, and electrochemical measurement. The as-cast Mg–9Li–3Al–1.6Y alloy with the average grain size of 325 lm is composed of b-Li matrix, block a-Mg, and granule Al2Y phases. After extrusion, the grain size of the as-cast alloy is obviously refined and reaches to 75 lm; the strength and elongation of the extruded alloy are enhanced by 17.20 % and49.45 %, respectively, owing to their fine microstructure and reduction of casting defects. The as-extruded alloy shows better corrosion resistance compared to the as-cast one, which may be related to the low stored energy and dislocation density in the extruded alloy, also the homogenization treatment before extrusion.展开更多
Metallic magnesium was prepared by vacuumassisted carbothermic reduction method, and its morphologies were observed and analyzed. The reduction ratios of reactions were carried out under various vacuums, reaction temp...Metallic magnesium was prepared by vacuumassisted carbothermic reduction method, and its morphologies were observed and analyzed. The reduction ratios of reactions were carried out under various vacuums, reaction temperatures, and time. Reaction kinetics of carbothermic reduction process was investigated. The results reveal that the morphologies of metallic magnesium sample that crystallized in the bottom and top sections of the condensation cap appear as the shape of feather with close-packing needle structure and the shape of schistose with metal luster,compactly clumpy structure, respectively. The reduction ratio of reaction process can be facilitated through reducing vacuum, increasing temperature, lengthening time, or their combinations and can reach up to 83.7 % under the condition of 10 Pa and 1573 K with 60 min reaction time. At1423-1573 K, the reaction rate constant k of carbothermic reduction of magnesia in vacuum gets greater with the increase of temperature. The reaction activity energy is190.28, 219.71 and 451.12-528.54 k J mol-1when the procedure of carbon gasification reaction, interfacial reaction, or gaseous diffusion is the reaction rate-determining step at 1423-1573 K, respectively. The gaseous diffusion procedure has the largest activity energy value and is,therefore, the main reaction rate-determining step.展开更多
基金the financial supports from the Fundamental Research Funds for the Central Universities,China(Nos.2019CDCGCL316,2020CDJDPT001)Chongqing Research Program of Basic Research and Frontier Technology,China(No.cstc2019jcjy-msxmX0539)。
文摘Mg−1Mn−0.5Al−0.5Ca−0.5Zn(wt.%)alloy was fabricated by conventional extrusion at 673 K with an extrusion ratio of 25:1,followed by aging at 473 K.The microstructure was characterized by scanning electron microscopy,electron back-scattered diffraction,and transmission electron microscopy.The mechanical properties were determined by the tensile test.The peak-aged sample shows fine recrystallized grains with an average grain size of 1.7μm.Area fraction of Al−Ca particles in the alloy increases significantly after peak aging.Meanwhile,botháañandác+añdislocations were observed to remain in the alloy after hot extrusion.Thus,the peak-aged sample exhibits simultaneously high strength and good ductility with the ultimate tensile stress,tensile yield stress,and tension fracture elongation of 320 MPa,314 MPa,and 19.0%,respectively.
基金appreciate the Ministry of Edu-cation of the People’s Republic of China and Chongqing University with National Undergraduates Innovating Experi-mentation Project 1210611007.
文摘The Gibbs free energy and critical reaction conditions of preparing Mg and Ca metal by carbothermic reducing calcined dolomite were calculated and analyzed.New thermodynamic criterion for reduction reaction,including the critical temperature and vacuum degree,was studied.The results show that:when T/P^(0.0449)<1199.2,neither MgO nor CaO can be reduced by carbon;when T/P^(0.0449)≥1199.2 and T/P^(0.0462)<1350.9,MgO can be reduced while CaO can not be;when T/P^(0.0462)≥1350.9,both MgO and CaO can be reduced.According to the requirements,we can obtain only Mg,Mg first then Ca,Mg and Ca simultaneously by controlling temperature,vacuum degree or both of them properly,by carbothermic reducing calcined dolomite.
基金financial support by the National Key Research and Development Program of China(Project Nos.2016YFB0301100 and 2016YFB0700403)the National Natural Science Foundation(Project No.51601024)+2 种基金the National Key Research,the Chongqing Research Program of Basic Research and Frontier Technology(Project No.cstc2016jcyj A0418)the National Natural Science Foundation of China(Grant No.51701026)the Fundamental Research Funds for the Central Universities(Project No.106112017CDJXY130001)
文摘The as-rolled AZ31 Mg alloy sheets are welded by friction stir welding(FSW) in this study, followed by annealing and hot rolling with different reductions. The effects of welding speed and the rolling reduction on the microstructure, tensile properties, microhardness and fracture surfaces of the specimens are investigated. The results show that the microstructures of the FSW joint in different regions become more and more consistent as the hot rolling reduction increases. The mechanical properties of the FSW joints and the joint coefficient are improved with increasing rolling reduction; however,the hardness value in the stirred zone decreases firstly and then increases. When the rolling reduction is 50%, the tensile strength of FSW joint is close to that of base metal. The sample L_3 achieves the best comprehensive properties, with the yield strength, ultimate tensile strength and elongation of 162, 287.9 MPa, and 17.9%, respectively.
基金supported by the National Natural Science Foundation of China(81530093,81773781,and 81803604)the Program for Changjiang Scholars and Innovative Research Team in University(PCSIRT,IRT_17R68)+3 种基金Beijing Outstanding Young Scientist Program(BJJWZYJH01201910023028)Shandong Provincial Natural Science Foundation(ZR2019MH001)the Fundamental Research Funds for the Central Universities(2019ZRJC004)CAMS Innovation Found for Medical Sciences(2016-I2M-1-007 and 2016-I2M-3-008).
文摘Dear Editor,The epithelial-to-mesenchymal transition(EMT)is a positive modulator of triple-negative breast cancer(TNBC)progression.1 Several EMT-inducing transcriptional factors(EMT-TFs)drive EMT process and enhance TNBC progression.2 Promoting the degradation of EMT-TFs to inhibit EMT and malignant actions holds therapeutic potential for TNBC patients.
基金financially supported by the National Basic Research Program of China (No. 2007CB613702)the International Scientific and Technological Cooperation Projects (No. 2010DFR50010)
文摘Mg–9Li–3Al–1.6Y alloys were prepared through mixture method. The microstructure, mechanical properties, and corrosion resistance of the as-cast and asextruded alloys were studied by optical microscopy(OM),scanning electronic microscopy(SEM), X-ray diffraction(XRD), mechanical properties testing, and electrochemical measurement. The as-cast Mg–9Li–3Al–1.6Y alloy with the average grain size of 325 lm is composed of b-Li matrix, block a-Mg, and granule Al2Y phases. After extrusion, the grain size of the as-cast alloy is obviously refined and reaches to 75 lm; the strength and elongation of the extruded alloy are enhanced by 17.20 % and49.45 %, respectively, owing to their fine microstructure and reduction of casting defects. The as-extruded alloy shows better corrosion resistance compared to the as-cast one, which may be related to the low stored energy and dislocation density in the extruded alloy, also the homogenization treatment before extrusion.
基金financially supported by the National Basic Research Program of China(No.2007CB613700)the International Scientific and Technological Cooperation Program(No.2010DFR50010)
文摘Metallic magnesium was prepared by vacuumassisted carbothermic reduction method, and its morphologies were observed and analyzed. The reduction ratios of reactions were carried out under various vacuums, reaction temperatures, and time. Reaction kinetics of carbothermic reduction process was investigated. The results reveal that the morphologies of metallic magnesium sample that crystallized in the bottom and top sections of the condensation cap appear as the shape of feather with close-packing needle structure and the shape of schistose with metal luster,compactly clumpy structure, respectively. The reduction ratio of reaction process can be facilitated through reducing vacuum, increasing temperature, lengthening time, or their combinations and can reach up to 83.7 % under the condition of 10 Pa and 1573 K with 60 min reaction time. At1423-1573 K, the reaction rate constant k of carbothermic reduction of magnesia in vacuum gets greater with the increase of temperature. The reaction activity energy is190.28, 219.71 and 451.12-528.54 k J mol-1when the procedure of carbon gasification reaction, interfacial reaction, or gaseous diffusion is the reaction rate-determining step at 1423-1573 K, respectively. The gaseous diffusion procedure has the largest activity energy value and is,therefore, the main reaction rate-determining step.