By adding different amounts of Ti into the electromagnetic stirred Al-18wt.%Mg_(2)Si alloy,the effect of Ti element on the microstructure and mechanical properties of the alloy was studied.The experimental results sho...By adding different amounts of Ti into the electromagnetic stirred Al-18wt.%Mg_(2)Si alloy,the effect of Ti element on the microstructure and mechanical properties of the alloy was studied.The experimental results show that the microstructure is refined after modification with Ti,which is related to the heterogeneous nucleation of TiAl_(3) particles on theα-Al matrix.With the increase of Ti content and holding time after stirring,the primary Mg_(2)Si phase is refined firstly and then coarsened,and correspondingly,the mechanical properties of the alloy show a trend of increasing at first and then decreasing.When the addition of Ti is 0.5wt.%and the holding time is about 20 min,the refinement effect of primary Mg_(2)Si phase is the most significant and the mechanical properties of the alloy are optimal.展开更多
The electrochemical behaviors and coupling behaviors of the Mg2Si and Si phases with α(Al) were investigated, the corrosion morphologies of Al alloys containing Mg2Si and Si particles were observed, and the corrosi...The electrochemical behaviors and coupling behaviors of the Mg2Si and Si phases with α(Al) were investigated, the corrosion morphologies of Al alloys containing Mg2Si and Si particles were observed, and the corrosion mechanism associated with them in Al-Mg-Si alloys was advanced. The results show that Si particle is always cathodic to the alloy base, Mg2Si is anodic to the alloy base and corrosion occurs on its surface at the beginning. However, during its corrosion process, the preferential dissolution of Mg and the enrichment of Si make Mg2Si transform to cathode from anode, leading to the anodic dissolution and corrosion of the alloy base at its adjacent periphery at a later stage. As the mole ratio of Mg to Si in an Al-Mg-Si alloy is less than 1.73, it contains Mg2Si and Si particles simultaneously in the grain boundary area, and corrosion initiates on the Mg2Si surface and the precipitate-free zone (PFZ) at the adjacent periphery of Si particle. As corrosion time is extended, Si particle leads to severe anodic dissolution and corrosion of the PFZ at its adjacent periphery, expedites the polarity transformation between Mg2Si and the PFZ and accelerates the corrosion of PFZ at the adjacent periphery of Mg2Si particle.展开更多
Hypereutectic Al-Si alloy with variant Mg contents were fabricated by casting,and the effects of Mg content on the microstructure of primary Mg2Si particles in hypereutectic Al-Si alloys were investigated.The results ...Hypereutectic Al-Si alloy with variant Mg contents were fabricated by casting,and the effects of Mg content on the microstructure of primary Mg2Si particles in hypereutectic Al-Si alloys were investigated.The results show that the volume fraction of primary Mg2Si particles increases linearly with raising the Mg content,but the average size of Mg2Si particles does not exhibit a corresponding change.When the Mg content is 3%,á1 0 0? directions have the fastest growth velocity,so that Mg2Si particles are likely to form octahedron shape.When gradually increasing the Mg content,the distributions of Mg and Si atoms on the solid-liquid interface become inhomogeneous,which results in the formation of irregular octahedron structures.Finally,when the Mg content is about 10%,the morphology of primary Mg2Si particles changes from the octahedron shape into various complex structures with a large size.展开更多
The effects of Sb and Sr on the modification and refinement of Mg17Al12 and Mg2Si phases in Mg- 12Al-0.7Si alloy were investigated and compared. The microstructure and mechanical properties of Mg-12Al0.7Si alloy and i...The effects of Sb and Sr on the modification and refinement of Mg17Al12 and Mg2Si phases in Mg- 12Al-0.7Si alloy were investigated and compared. The microstructure and mechanical properties of Mg-12Al0.7Si alloy and its modification mechanism by Sb and Sr were investigated using a scanning electron microscope (SEM), an energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and differential thermal analysis (DTA). The results indicate that by adding 0.5wt.% Sb to the Mg-12Al-0.7Si alloy, the Mg17Al12 phase was refined and broken into some discontinuous island structures. However, some network Mg17Al12 phases still can be detected in Mg-12Al-0.7Si-0.09Sr alloy. Therefore, Sb performs better in modification and refinement of Mg17Al12 phase than does Sr. Small amounts of fine polygonal shaped Mg2Si phases were found in Mg-12AI-0.7Si-0.5Sb alloy, while the morphology of Mg2Si phases in Mg-12Al-0.7Si-0.09Sr alloy changed from the coarse Chinese script shapes to fine granule and irregular polygonal shapes, indicating that the effects of modification and refinement on Mg2Si phase are more significant by adding 0.09wt.% Sr than 0.5wt.% Sb. The ultimate tensile strengths of the Sb and Sr modified Mg-12Al-0.7Si alloys were considerably increased both at room temperature and at 200 ℃.展开更多
The effects of Si content on the microstructure and yield strength of Al-(1.44-12.40)Si-0.7 Mg(wt.%)alloy sheets under the T4 condition were systematically studied via laser scanning confocal microscopy(LSCM),DSC,TEM ...The effects of Si content on the microstructure and yield strength of Al-(1.44-12.40)Si-0.7 Mg(wt.%)alloy sheets under the T4 condition were systematically studied via laser scanning confocal microscopy(LSCM),DSC,TEM and tensile tests.The results show that the recrystallization grain of the alloy sheets becomes more refined with an increase in Si content.When the Si content increases from 1.44 to 12.4 wt.%,the grain size of the alloy sheets decreases from approximately 47 to 10μm.Further,with an increase in Si content,the volume fraction of the GP zones in the matrix increases slightly.Based on the existing model,a yield strength model for alloy sheets was proposed.The predicted results are in good agreement with the actual experimental results and reveal the strengthening mechanisms of the Al-(1.44-12.40)Si-0.7 Mg alloy sheets under the T4 condition and how they are influenced by the Si content.展开更多
Finite element analysis has been carried out to understand the effect of various processing routes and condition on the microscale deformation behavior of Al–4.5 Cu–2 Mg alloy. The alloy has been developed through f...Finite element analysis has been carried out to understand the effect of various processing routes and condition on the microscale deformation behavior of Al–4.5 Cu–2 Mg alloy. The alloy has been developed through four different routes and condition, i.e. conventional gravity casting with and without refiner, rheocasting and SIMA process. The optical microstructures of the alloy have been used to develop representative volume elements(RVEs). Two different boundary conditions have been employed to simulate the deformation behavior of the alloy under uniaxial loading. Finally, the simulated stress-strain behavior of the alloy is compared with the experimental result. It is found that the microstructural morphology has a significant impact on stress and strain distribution and load carrying capacity. The eutectic phase always carries a higher load than the α(Al) phase. The globular α(Al) grains with thinner and uniformly distributed eutectic network provide a better stress and strain distribution. Owing to this, SIMA processed alloy has better stress and strain distribution than other processes. Finally, the simulated yield strength of the alloy is verified by experiment and they have great agreement.展开更多
A modification of Mg2Si in the hypereutectic Mg-4%Si alloy(mass fraction) with Sr was investigated.Two types of Mg2Si in the alloys were found:polygonal primary Mg2Si and Chinese script type eutectic Mg2Si.Adding A...A modification of Mg2Si in the hypereutectic Mg-4%Si alloy(mass fraction) with Sr was investigated.Two types of Mg2Si in the alloys were found:polygonal primary Mg2Si and Chinese script type eutectic Mg2Si.Adding Al-10% Sr master alloy to the Mg-4%Si alloy clearly reduced the average size of primary Mg2Si and changed the morphology of eutectic Mg2Si from Chinese script type to polyhedral or fine fibre shape.The refinement of primary Mg2Si is mainly attributed to the heterogeneous nucleation mechanism induced by the Sr-rich particles.The modification of eutectic Mg2Si results from the dissolved Sr,which alters the preferred growth manner of the eutectic.展开更多
The modification effect of neodymium (Nd) on Mg2Si in the hypereutectic Mg-3%Si (mass fraction) alloy was investigated by optical microcopy, scanning electron microscopy and X-ray diffraction. The results indicate...The modification effect of neodymium (Nd) on Mg2Si in the hypereutectic Mg-3%Si (mass fraction) alloy was investigated by optical microcopy, scanning electron microscopy and X-ray diffraction. The results indicate that the morphology of the primary Mg2Si transforms from coarse dendrite into fine polygon with increasing Nd content. The average size of the primary Mg2Si significantly decreases to about 10 ~ma with increasing Nd content up to 1.0%, and then becomes coarser again. The modification and refinement of the primary Mg2Si are mainly attributed to the poisoning effect. The NdMg2 phase in the primary Mg2Si transforms into NdSi and NdSi2 compounds as the Nd content exceeds 3.0%. Therefore, it is reasonable to conclude that the proper Nd (1.0%) addition can effectively modify and refine the primary Mg2Si.展开更多
基金financially supported by the Science and Technology Development Program of Shouguang(No.2019JH14)the Science and Technology Development Program of Weifang(No.2021GX052)the Natural Science Foundation of Liaoning Province(No.080137)。
文摘By adding different amounts of Ti into the electromagnetic stirred Al-18wt.%Mg_(2)Si alloy,the effect of Ti element on the microstructure and mechanical properties of the alloy was studied.The experimental results show that the microstructure is refined after modification with Ti,which is related to the heterogeneous nucleation of TiAl_(3) particles on theα-Al matrix.With the increase of Ti content and holding time after stirring,the primary Mg_(2)Si phase is refined firstly and then coarsened,and correspondingly,the mechanical properties of the alloy show a trend of increasing at first and then decreasing.When the addition of Ti is 0.5wt.%and the holding time is about 20 min,the refinement effect of primary Mg_(2)Si phase is the most significant and the mechanical properties of the alloy are optimal.
基金Project (21073162) supported by the National Natural Science Foundation of ChinaProject (2008) supported by the Scientific and Technological Projects of Ningxia, China+1 种基金Project (08JC1421600) supported by the Science and Technology Commission of Shanghai Municipality, ChinaProject (2008AZ2018) supported by the Science and Technology Bureau of Jiaxing City, China
文摘The electrochemical behaviors and coupling behaviors of the Mg2Si and Si phases with α(Al) were investigated, the corrosion morphologies of Al alloys containing Mg2Si and Si particles were observed, and the corrosion mechanism associated with them in Al-Mg-Si alloys was advanced. The results show that Si particle is always cathodic to the alloy base, Mg2Si is anodic to the alloy base and corrosion occurs on its surface at the beginning. However, during its corrosion process, the preferential dissolution of Mg and the enrichment of Si make Mg2Si transform to cathode from anode, leading to the anodic dissolution and corrosion of the alloy base at its adjacent periphery at a later stage. As the mole ratio of Mg to Si in an Al-Mg-Si alloy is less than 1.73, it contains Mg2Si and Si particles simultaneously in the grain boundary area, and corrosion initiates on the Mg2Si surface and the precipitate-free zone (PFZ) at the adjacent periphery of Si particle. As corrosion time is extended, Si particle leads to severe anodic dissolution and corrosion of the PFZ at its adjacent periphery, expedites the polarity transformation between Mg2Si and the PFZ and accelerates the corrosion of PFZ at the adjacent periphery of Mg2Si particle.
基金Project(CDJZR12240056)supported by the Fundamental Research Funds for Central Universities,ChinaProject(cstc2013jcyj A50014)supported by the Foundational and Cutting-edge Research Plan of Chongqing,China
文摘Hypereutectic Al-Si alloy with variant Mg contents were fabricated by casting,and the effects of Mg content on the microstructure of primary Mg2Si particles in hypereutectic Al-Si alloys were investigated.The results show that the volume fraction of primary Mg2Si particles increases linearly with raising the Mg content,but the average size of Mg2Si particles does not exhibit a corresponding change.When the Mg content is 3%,á1 0 0? directions have the fastest growth velocity,so that Mg2Si particles are likely to form octahedron shape.When gradually increasing the Mg content,the distributions of Mg and Si atoms on the solid-liquid interface become inhomogeneous,which results in the formation of irregular octahedron structures.Finally,when the Mg content is about 10%,the morphology of primary Mg2Si particles changes from the octahedron shape into various complex structures with a large size.
基金financially supported by the National Natural Science Foundation of China(Grant nos.:51301118,51404166)the Projects of International Cooperation in Shanxi province,China(Grant no.:2014081002)and the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi province,China(Grant nos.:2013108,2014120)
文摘The effects of Sb and Sr on the modification and refinement of Mg17Al12 and Mg2Si phases in Mg- 12Al-0.7Si alloy were investigated and compared. The microstructure and mechanical properties of Mg-12Al0.7Si alloy and its modification mechanism by Sb and Sr were investigated using a scanning electron microscope (SEM), an energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and differential thermal analysis (DTA). The results indicate that by adding 0.5wt.% Sb to the Mg-12Al-0.7Si alloy, the Mg17Al12 phase was refined and broken into some discontinuous island structures. However, some network Mg17Al12 phases still can be detected in Mg-12Al-0.7Si-0.09Sr alloy. Therefore, Sb performs better in modification and refinement of Mg17Al12 phase than does Sr. Small amounts of fine polygonal shaped Mg2Si phases were found in Mg-12AI-0.7Si-0.5Sb alloy, while the morphology of Mg2Si phases in Mg-12Al-0.7Si-0.09Sr alloy changed from the coarse Chinese script shapes to fine granule and irregular polygonal shapes, indicating that the effects of modification and refinement on Mg2Si phase are more significant by adding 0.09wt.% Sr than 0.5wt.% Sb. The ultimate tensile strengths of the Sb and Sr modified Mg-12Al-0.7Si alloys were considerably increased both at room temperature and at 200 ℃.
基金Project(2016YFB0300801)supported by the National Key Research and Development Program of ChinaProject(51871043)supported by the National Natural Science Foundation of ChinaProject(N180212010)supported by the Fundamental Research Funds for the Central Universities of China。
文摘The effects of Si content on the microstructure and yield strength of Al-(1.44-12.40)Si-0.7 Mg(wt.%)alloy sheets under the T4 condition were systematically studied via laser scanning confocal microscopy(LSCM),DSC,TEM and tensile tests.The results show that the recrystallization grain of the alloy sheets becomes more refined with an increase in Si content.When the Si content increases from 1.44 to 12.4 wt.%,the grain size of the alloy sheets decreases from approximately 47 to 10μm.Further,with an increase in Si content,the volume fraction of the GP zones in the matrix increases slightly.Based on the existing model,a yield strength model for alloy sheets was proposed.The predicted results are in good agreement with the actual experimental results and reveal the strengthening mechanisms of the Al-(1.44-12.40)Si-0.7 Mg alloy sheets under the T4 condition and how they are influenced by the Si content.
文摘Finite element analysis has been carried out to understand the effect of various processing routes and condition on the microscale deformation behavior of Al–4.5 Cu–2 Mg alloy. The alloy has been developed through four different routes and condition, i.e. conventional gravity casting with and without refiner, rheocasting and SIMA process. The optical microstructures of the alloy have been used to develop representative volume elements(RVEs). Two different boundary conditions have been employed to simulate the deformation behavior of the alloy under uniaxial loading. Finally, the simulated stress-strain behavior of the alloy is compared with the experimental result. It is found that the microstructural morphology has a significant impact on stress and strain distribution and load carrying capacity. The eutectic phase always carries a higher load than the α(Al) phase. The globular α(Al) grains with thinner and uniformly distributed eutectic network provide a better stress and strain distribution. Owing to this, SIMA processed alloy has better stress and strain distribution than other processes. Finally, the simulated yield strength of the alloy is verified by experiment and they have great agreement.
基金Project(2011BAE22B00) supported by the National Key Technology R&D Program of ChinaProjects(ZR2010EQ021,ZR2010EL013) supported by the Natural Science Foundation of Shandong Province,China
文摘A modification of Mg2Si in the hypereutectic Mg-4%Si alloy(mass fraction) with Sr was investigated.Two types of Mg2Si in the alloys were found:polygonal primary Mg2Si and Chinese script type eutectic Mg2Si.Adding Al-10% Sr master alloy to the Mg-4%Si alloy clearly reduced the average size of primary Mg2Si and changed the morphology of eutectic Mg2Si from Chinese script type to polyhedral or fine fibre shape.The refinement of primary Mg2Si is mainly attributed to the heterogeneous nucleation mechanism induced by the Sr-rich particles.The modification of eutectic Mg2Si results from the dissolved Sr,which alters the preferred growth manner of the eutectic.
基金Project(A0420110401)supported by the National Security Basic Research,China
文摘The modification effect of neodymium (Nd) on Mg2Si in the hypereutectic Mg-3%Si (mass fraction) alloy was investigated by optical microcopy, scanning electron microscopy and X-ray diffraction. The results indicate that the morphology of the primary Mg2Si transforms from coarse dendrite into fine polygon with increasing Nd content. The average size of the primary Mg2Si significantly decreases to about 10 ~ma with increasing Nd content up to 1.0%, and then becomes coarser again. The modification and refinement of the primary Mg2Si are mainly attributed to the poisoning effect. The NdMg2 phase in the primary Mg2Si transforms into NdSi and NdSi2 compounds as the Nd content exceeds 3.0%. Therefore, it is reasonable to conclude that the proper Nd (1.0%) addition can effectively modify and refine the primary Mg2Si.