The deformation behaviors of a new quaternary Mg-6Zn-1.5Cu-0.5Zr alloy at temperatures of 523-673 K and strain rates of 0.001-1 s-1 were studied by compressive tests using a Gleeble 3800 thermal-simulator.The results ...The deformation behaviors of a new quaternary Mg-6Zn-1.5Cu-0.5Zr alloy at temperatures of 523-673 K and strain rates of 0.001-1 s-1 were studied by compressive tests using a Gleeble 3800 thermal-simulator.The results show that the flow stress increases as the deformation temperature decreases or as the strain rate increases.A strain-dependent constitutive equation and a feed-forward back-propagation artificial neural network were used to predict flow stress,which showed good agreement with experimental data.The processing map suggests that the domains of 643-673 K and 0.001-0.01 s-1 are corresponded to optimum conditions for hot working of the T4-treated Mg-6Zn-1.5Cu-0.5Zr alloy.展开更多
The effects of Ce addition on the microstructure, age hardening response and mechanical properties of an indirect-extruded Mg-5wt.%Sn-4Zn (TZ54) alloy were investigated. Addition of Ce accelerated the aging response w...The effects of Ce addition on the microstructure, age hardening response and mechanical properties of an indirect-extruded Mg-5wt.%Sn-4Zn (TZ54) alloy were investigated. Addition of Ce accelerated the aging response with the peak aging time moving from 300 h in TZ54 to 30 h in Mg-5wt.%Sn-4Zn-1Ce (TZE541), while the peak harness was similar to each other. The addition of Ce also caused an increase in the precipitation stability during overageing. Though the tensile strength of extruded TZ54 was improved by t...展开更多
The phase evolution in （88%-91%）Mg-8%Sn-l%Zn-X （X=A1, Mn and/or Ce） system was analyzed via CALPHAD method and simulations were used in precise selection of the chemical composition. The influence of the addition ...The phase evolution in （88%-91%）Mg-8%Sn-l%Zn-X （X=A1, Mn and/or Ce） system was analyzed via CALPHAD method and simulations were used in precise selection of the chemical composition. The influence of the addition of different alloying elements such as A1, Mn and Ce on the microstructure and microhardness of Mg-8%Sn-l%Zn-based alloys was investigated. Combined addition of A1 and Mn shows features distinct from separate addition of A1 or Mn. Additions of l%AI and l%Mn to base alloy result in the formation of massive A1-Mn phase in a-Mg matrix grains. Addition of Ce element can refme the second eutectic precipitates and form intermetallic compounds with Sn. Fine rod-like Sn-Ce phase presents mainly on the grain boundaries and plays a role in inhibiting grain growth. The effects of alloying elements on Vickers microhardness and indentation size effect of base alloy were examined.展开更多
Mg-Zn-Y-based quasi-crystal （QC） alloys were fabricated by pouring melts into different cooling media. The effects of different cooling rates on the QC morphology, size, volume fraction and micro-hardness were studi...Mg-Zn-Y-based quasi-crystal （QC） alloys were fabricated by pouring melts into different cooling media. The effects of different cooling rates on the QC morphology, size, volume fraction and micro-hardness were studied. Multi-component Mg-Zn-Y-based QC alloys were synthesized based on amorphous design principle. QC morphology transformation and its influencing factors were analyzed. Micro/nano spherical quasi-crystals （QCs） were fabricated through a wedge-shaped copper mould and their forming mechanism were discussed by atoms cluster theory, optimum cooling rate theory and the known crucial criteria. The results of research show that with the cooling rate reduced, the solidified morphology of QC phase changes from near-spherical, micro petals （1 to 2 um） to big petals （20 um） and finally grows up to bulk pentagon or hexagon （200 to 400 um）. Multi-component micro-spherical QCs possess higher value of micro-hardness than petal-like QCs with the same components, and also higher than ternary micro-Mg-Zn-Y QCs. The fine master alloys containing micro-QCs （0.4 um） and nano-QCs （about 300 nm and 40 nm） have been fabricated correspondingly on the middle and the tip of wedge-shaped castings. A morphology evolution schematic diagram of Mg-Zn-Y-based QCs is included in this paper.展开更多
基金supported by the R&D Program of Korea Institute of Materials Sciencethe World Premier Materials Program funded by The Ministry of Knowledge Economy,Koreasupport from China Scholarship Council(CSC)
文摘The deformation behaviors of a new quaternary Mg-6Zn-1.5Cu-0.5Zr alloy at temperatures of 523-673 K and strain rates of 0.001-1 s-1 were studied by compressive tests using a Gleeble 3800 thermal-simulator.The results show that the flow stress increases as the deformation temperature decreases or as the strain rate increases.A strain-dependent constitutive equation and a feed-forward back-propagation artificial neural network were used to predict flow stress,which showed good agreement with experimental data.The processing map suggests that the domains of 643-673 K and 0.001-0.01 s-1 are corresponded to optimum conditions for hot working of the T4-treated Mg-6Zn-1.5Cu-0.5Zr alloy.
基金Project supported by the Fundamental R&D Program for Core Technology of Materials Funded by the Ministry of Knowledge Economy and the Center for Advanced Materials Processing (CAMP) of 21st Century Frontier R&D Program, Republic of Korea
文摘The effects of Ce addition on the microstructure, age hardening response and mechanical properties of an indirect-extruded Mg-5wt.%Sn-4Zn (TZ54) alloy were investigated. Addition of Ce accelerated the aging response with the peak aging time moving from 300 h in TZ54 to 30 h in Mg-5wt.%Sn-4Zn-1Ce (TZE541), while the peak harness was similar to each other. The addition of Ce also caused an increase in the precipitation stability during overageing. Though the tensile strength of extruded TZ54 was improved by t...
文摘The phase evolution in （88%-91%）Mg-8%Sn-l%Zn-X （X=A1, Mn and/or Ce） system was analyzed via CALPHAD method and simulations were used in precise selection of the chemical composition. The influence of the addition of different alloying elements such as A1, Mn and Ce on the microstructure and microhardness of Mg-8%Sn-l%Zn-based alloys was investigated. Combined addition of A1 and Mn shows features distinct from separate addition of A1 or Mn. Additions of l%AI and l%Mn to base alloy result in the formation of massive A1-Mn phase in a-Mg matrix grains. Addition of Ce element can refme the second eutectic precipitates and form intermetallic compounds with Sn. Fine rod-like Sn-Ce phase presents mainly on the grain boundaries and plays a role in inhibiting grain growth. The effects of alloying elements on Vickers microhardness and indentation size effect of base alloy were examined.
基金supported by Natural Science Foundation of Hebei Province, China (E2010000057, E2010000121, E2012202017)International S & T Cooperation Program of China (2010DFA51850)
文摘Mg-Zn-Y-based quasi-crystal （QC） alloys were fabricated by pouring melts into different cooling media. The effects of different cooling rates on the QC morphology, size, volume fraction and micro-hardness were studied. Multi-component Mg-Zn-Y-based QC alloys were synthesized based on amorphous design principle. QC morphology transformation and its influencing factors were analyzed. Micro/nano spherical quasi-crystals （QCs） were fabricated through a wedge-shaped copper mould and their forming mechanism were discussed by atoms cluster theory, optimum cooling rate theory and the known crucial criteria. The results of research show that with the cooling rate reduced, the solidified morphology of QC phase changes from near-spherical, micro petals （1 to 2 um） to big petals （20 um） and finally grows up to bulk pentagon or hexagon （200 to 400 um）. Multi-component micro-spherical QCs possess higher value of micro-hardness than petal-like QCs with the same components, and also higher than ternary micro-Mg-Zn-Y QCs. The fine master alloys containing micro-QCs （0.4 um） and nano-QCs （about 300 nm and 40 nm） have been fabricated correspondingly on the middle and the tip of wedge-shaped castings. A morphology evolution schematic diagram of Mg-Zn-Y-based QCs is included in this paper.
