Fine-grain Mg95.50Zn3.71Y0.79 alloy was prepared by high pressure solidification. By comparison with the conventional cast-ing alloy, the true stress-strain curve characteristic and deformation microstructure of Mg95....Fine-grain Mg95.50Zn3.71Y0.79 alloy was prepared by high pressure solidification. By comparison with the conventional cast-ing alloy, the true stress-strain curve characteristic and deformation microstructure of Mg95.50Zn3.71Y0.79 alloy solidified under high pressure were studied via unilateralism compress tests under the strain rate of 0.001–1 s–1 and deformation temperature of 523–623 K. Constitutive equations were constructed. According to the experimental results, compared to the conventional casting alloy, the true stress-strain curve of the fine-grain alloy solidified under high pressure not only had the high strain hardening characteristic but the dynamic recrystallization softening after the peak stress was more than the working hardening and would soon reach a stable flow stress - strain state. The deformation activation energy of the alloy solidified under high pressure was 151 kJ/mol, around 49 kJ/mol lower than that of the conventional casting alloy. The fine-grain Mg-Zn-Y alloy solidified under high pressure could obtain 95 percent of dynamic recrystallization grain at 573 K during hot deformation process.展开更多
The non-equilibrium microstructure and a new metastable phase of Al-9.6wt%Mg alloy solidified at 6 GPa were studied by optical microscope,differential scanning calorimetry,X-ray diffraction and transmission electron m...The non-equilibrium microstructure and a new metastable phase of Al-9.6wt%Mg alloy solidified at 6 GPa were studied by optical microscope,differential scanning calorimetry,X-ray diffraction and transmission electron microscope.The results showed that dendrite microstructure was refined,and the solid solubility of Mg in α-Al phase increased greatly.Correspondingly,the lattice parameter of α-Al phase increased.Al3Mg2 phases disappeared under high pressure solidification.In particular,a metastable phase with small size(20 nm or so) was produced in the alloy,its melting temperature range was 464～518.2 ℃,which was higher than that of Al3Mg2 phase(453～465 ℃) under normal pressure.These metastable phases located in the interdendritic position.It was the first time that the metastable phase was found in Al-Mg alloy at a high pressure of 6 GPa.The formation mechanism of the metastable phases was discussed.展开更多
High pressure solidification rules of Al-Mg alloy needs to be discussed further for its wide range of application. Microstructures and phases of Al-25wt% Mg alloy solidified at 4 GPa were studied by optical microscope...High pressure solidification rules of Al-Mg alloy needs to be discussed further for its wide range of application. Microstructures and phases of Al-25wt% Mg alloy solidified at 4 GPa were studied by optical microscope,X-ray diffractmeter,energy dispersive X-ray spectroscopy and transmission electron microscopy( TEM). The microstructure evolution mechanism of Al-25Mg alloy under high pressure was analyzed. The result shows that the alloy consists of α-Al phase and Al 3 Mg 2 phase under normal pressure. However,only Al 12 Mg 17 phase forms without Al 3 Mg 2 phase at 4 GPa. In addition,Mg concentration in α-Al phase increases and that of the lattice constant also increases. The α-Al dendrite presents the broken arms under normal pressure, after high pressure solidification,the morphology of the dendrite tends to integrate and the size of the dendrite arms展开更多
基金Project supported by National Natural Science Foundation of China(51475486)Hebei Province Natural Science Fund(E2013501096)
文摘Fine-grain Mg95.50Zn3.71Y0.79 alloy was prepared by high pressure solidification. By comparison with the conventional cast-ing alloy, the true stress-strain curve characteristic and deformation microstructure of Mg95.50Zn3.71Y0.79 alloy solidified under high pressure were studied via unilateralism compress tests under the strain rate of 0.001–1 s–1 and deformation temperature of 523–623 K. Constitutive equations were constructed. According to the experimental results, compared to the conventional casting alloy, the true stress-strain curve of the fine-grain alloy solidified under high pressure not only had the high strain hardening characteristic but the dynamic recrystallization softening after the peak stress was more than the working hardening and would soon reach a stable flow stress - strain state. The deformation activation energy of the alloy solidified under high pressure was 151 kJ/mol, around 49 kJ/mol lower than that of the conventional casting alloy. The fine-grain Mg-Zn-Y alloy solidified under high pressure could obtain 95 percent of dynamic recrystallization grain at 573 K during hot deformation process.
基金This work is financially supported by the Science Foundation of Harbin Institute of Technology ( No HIT2002 29)
文摘The non-equilibrium microstructure and a new metastable phase of Al-9.6wt%Mg alloy solidified at 6 GPa were studied by optical microscope,differential scanning calorimetry,X-ray diffraction and transmission electron microscope.The results showed that dendrite microstructure was refined,and the solid solubility of Mg in α-Al phase increased greatly.Correspondingly,the lattice parameter of α-Al phase increased.Al3Mg2 phases disappeared under high pressure solidification.In particular,a metastable phase with small size(20 nm or so) was produced in the alloy,its melting temperature range was 464～518.2 ℃,which was higher than that of Al3Mg2 phase(453～465 ℃) under normal pressure.These metastable phases located in the interdendritic position.It was the first time that the metastable phase was found in Al-Mg alloy at a high pressure of 6 GPa.The formation mechanism of the metastable phases was discussed.
基金Sponsored by the Scientific Research Foundation of Heilongjiang Institute of Science and Technology for the Introduction of High-Qualified Talents(Grant No.08-12)Department of Education of Heilongjiang Province Science and Technology Research Projects(Grant No.12523042)
文摘High pressure solidification rules of Al-Mg alloy needs to be discussed further for its wide range of application. Microstructures and phases of Al-25wt% Mg alloy solidified at 4 GPa were studied by optical microscope,X-ray diffractmeter,energy dispersive X-ray spectroscopy and transmission electron microscopy( TEM). The microstructure evolution mechanism of Al-25Mg alloy under high pressure was analyzed. The result shows that the alloy consists of α-Al phase and Al 3 Mg 2 phase under normal pressure. However,only Al 12 Mg 17 phase forms without Al 3 Mg 2 phase at 4 GPa. In addition,Mg concentration in α-Al phase increases and that of the lattice constant also increases. The α-Al dendrite presents the broken arms under normal pressure, after high pressure solidification,the morphology of the dendrite tends to integrate and the size of the dendrite arms
