Through morphology observation on silicon particles of Al-Si-Cu-Mg cast alloy, it is found that during solution treatment the evolution of eutectic silicon morphology and their effect on mechanical properties can be c...Through morphology observation on silicon particles of Al-Si-Cu-Mg cast alloy, it is found that during solution treatment the evolution of eutectic silicon morphology and their effect on mechanical properties can be classified into three stages. In the initial stage, necking, stubbing and fragmentation of silicon particles result in the improvement of plasticity of alloy. In the intermediate stage, the mechanical properties of 354 alloy attain peak values due to spheroidization of silicon particles. In the final stage, the drop of hardness and strength is related to the deterioration of silicon morphology. The facets and lap occur in silicon particles and the coarsening process of silicon follows LSW model. During aging, the clusters of excess silicon can work as barriers for dislocation movement and thus enhance the strength of alloy. On the other hand, excess Si affects the process of aging precipitation and leads to a fine and highly dense distribution of GP zones, finally effectively strengthens the alloy.展开更多
Based on the industrial production of non-oriented silicon steel,calcium treatment by CaSi wire feeding during the RH refining process was studied. The thermodynamics of CaS inclusion formation was analyzed, and the m...Based on the industrial production of non-oriented silicon steel,calcium treatment by CaSi wire feeding during the RH refining process was studied. The thermodynamics of CaS inclusion formation was analyzed, and the morphology and the size distribution were observed. Furthermore, the change in inclusion characteristics after calcium treatment and the effect of calcium treatment on magnetic properties were discussed. The results show that the formation of MnS and A1N inclusions were restrained, and the aggregating, floating and removing of microinclusions after calcium treatment were effectively promoted. The cleanliness of liquid steel was obviously increased. The main type of inclusions was single phase of CaO, with some complex inclusions composed of CaO, SiO2 and MgO. No CaS inclusion was observed after an appropriate calcium treatment. The size of all inclusions was distributed in the range of 2 - 20 μm, and the number was about 1.8 × 10^5/mm3. In addition, as an increasing amount of calcium was added,the core loss gradually decreased to a stable level, and the magnetic induction decreased quickly after a slow increase. The optimal calcium treatment mode depends on the chemical composition of steel.展开更多
In this work we are interested in studying the effect of the heat treatments on the dopant segregation at the grain boundaries in the polycrystalline silicon films. The obtained results have shown that the heat treatm...In this work we are interested in studying the effect of the heat treatments on the dopant segregation at the grain boundaries in the polycrystalline silicon films. The obtained results have shown that the heat treatments reduce the number of segregation sites at the grains boundaries, and consequently they limit the structural changes that can appear there and the quantity of the dope atoms that can accumulate in these boundaries. In addition they are more and more dopant that are found inside the grains when the temperature of the heat treatment increases. On the other hand, we established that the arsenic atoms have a strong tendency to the segregation than the boron atoms, and we have noticed a strong migration of arsenic atoms from the boundaries towards the grains under the effect of the heat treatments. It was also shown that the segregation of arsenic atoms at the grains boundaries is about 4 times higher than that of the boron atoms.展开更多
Based on the industrial production of non-oriented silicon steel, the rare earth （RE） treatment during the Ruhrstahl Heraeus （RH） refining process was studied. The morphology and the size distribution were observe...Based on the industrial production of non-oriented silicon steel, the rare earth （RE） treatment during the Ruhrstahl Heraeus （RH） refining process was studied. The morphology and the size distribution were observed for the steel specimens treated with different RE treatment conditions. Furthermore, the formation and change of the nonmetallic inclusion characteristics of finished steel sheets after the RE treatment were discussed. The results have shown that in the present work,the suitable RE metal additions are 0.6 -0.9 kg/t steel. After the suitable RE treatment,the formation of AIN and MnS inclusions were restrained, and the aggregation, flotation and removal of nonmetallic inclusions were efficiently promoted and the cleanliness of liquid steel was significantly increased. Meanwhile, the total oxygen concentration reached the minimum value and thle desulfurization efficiency was optimal ,and the type of main inclusions was approximately spherical or elliptical spherical RE radicle inclusions whose size was relatively large.展开更多
The effect of Si addition and heat treatment on the Al-5wt.%Fe alloy has been investigated by OM, SEM-EDS and XRD. The results show that the Si plays a significant role in refining the primary Al3 Fe phase. It was fou...The effect of Si addition and heat treatment on the Al-5wt.%Fe alloy has been investigated by OM, SEM-EDS and XRD. The results show that the Si plays a significant role in refining the primary Al3 Fe phase. It was found that the addition of 3.0wt.% Si made the alloy present the finest and well-distributed primary Al3 Fe phase, but the Al3 Fe phase almost disappeared when 5wt.% Si was added. With further increase in the Si content, some Fe-rich phases appeared in the inter-grains and coarsened. In addition, the heat treatments exert a significant impact on the microstructural evolution of the Al-5wt.%Fe-5wt.%Si alloy. After heat treatment for 28 hours at 590 oC, the coarse platelet or blocky Fe-rich phase in Al-5wt.%Fe-5wt.%Si alloys was granulated; the phase transformation from metastable platelet Al3 FeSi and blocky Al8Fe2 Si to stable Al5 FeSi had occurred. With the extension of heat treatment, the Si phase coarsened gradually.展开更多
文摘Through morphology observation on silicon particles of Al-Si-Cu-Mg cast alloy, it is found that during solution treatment the evolution of eutectic silicon morphology and their effect on mechanical properties can be classified into three stages. In the initial stage, necking, stubbing and fragmentation of silicon particles result in the improvement of plasticity of alloy. In the intermediate stage, the mechanical properties of 354 alloy attain peak values due to spheroidization of silicon particles. In the final stage, the drop of hardness and strength is related to the deterioration of silicon morphology. The facets and lap occur in silicon particles and the coarsening process of silicon follows LSW model. During aging, the clusters of excess silicon can work as barriers for dislocation movement and thus enhance the strength of alloy. On the other hand, excess Si affects the process of aging precipitation and leads to a fine and highly dense distribution of GP zones, finally effectively strengthens the alloy.
文摘Based on the industrial production of non-oriented silicon steel,calcium treatment by CaSi wire feeding during the RH refining process was studied. The thermodynamics of CaS inclusion formation was analyzed, and the morphology and the size distribution were observed. Furthermore, the change in inclusion characteristics after calcium treatment and the effect of calcium treatment on magnetic properties were discussed. The results show that the formation of MnS and A1N inclusions were restrained, and the aggregating, floating and removing of microinclusions after calcium treatment were effectively promoted. The cleanliness of liquid steel was obviously increased. The main type of inclusions was single phase of CaO, with some complex inclusions composed of CaO, SiO2 and MgO. No CaS inclusion was observed after an appropriate calcium treatment. The size of all inclusions was distributed in the range of 2 - 20 μm, and the number was about 1.8 × 10^5/mm3. In addition, as an increasing amount of calcium was added,the core loss gradually decreased to a stable level, and the magnetic induction decreased quickly after a slow increase. The optimal calcium treatment mode depends on the chemical composition of steel.
文摘In this work we are interested in studying the effect of the heat treatments on the dopant segregation at the grain boundaries in the polycrystalline silicon films. The obtained results have shown that the heat treatments reduce the number of segregation sites at the grains boundaries, and consequently they limit the structural changes that can appear there and the quantity of the dope atoms that can accumulate in these boundaries. In addition they are more and more dopant that are found inside the grains when the temperature of the heat treatment increases. On the other hand, we established that the arsenic atoms have a strong tendency to the segregation than the boron atoms, and we have noticed a strong migration of arsenic atoms from the boundaries towards the grains under the effect of the heat treatments. It was also shown that the segregation of arsenic atoms at the grains boundaries is about 4 times higher than that of the boron atoms.
文摘Based on the industrial production of non-oriented silicon steel, the rare earth （RE） treatment during the Ruhrstahl Heraeus （RH） refining process was studied. The morphology and the size distribution were observed for the steel specimens treated with different RE treatment conditions. Furthermore, the formation and change of the nonmetallic inclusion characteristics of finished steel sheets after the RE treatment were discussed. The results have shown that in the present work,the suitable RE metal additions are 0.6 -0.9 kg/t steel. After the suitable RE treatment,the formation of AIN and MnS inclusions were restrained, and the aggregation, flotation and removal of nonmetallic inclusions were efficiently promoted and the cleanliness of liquid steel was significantly increased. Meanwhile, the total oxygen concentration reached the minimum value and thle desulfurization efficiency was optimal ,and the type of main inclusions was approximately spherical or elliptical spherical RE radicle inclusions whose size was relatively large.
基金supported financially by the Strategic Priority Research Program CAS under Grant No.XDA03010304the National Natural Science Foundation of China under Grant No.91226204the Youth Innovation Promotion Association CAS
文摘The effect of Si addition and heat treatment on the Al-5wt.%Fe alloy has been investigated by OM, SEM-EDS and XRD. The results show that the Si plays a significant role in refining the primary Al3 Fe phase. It was found that the addition of 3.0wt.% Si made the alloy present the finest and well-distributed primary Al3 Fe phase, but the Al3 Fe phase almost disappeared when 5wt.% Si was added. With further increase in the Si content, some Fe-rich phases appeared in the inter-grains and coarsened. In addition, the heat treatments exert a significant impact on the microstructural evolution of the Al-5wt.%Fe-5wt.%Si alloy. After heat treatment for 28 hours at 590 oC, the coarse platelet or blocky Fe-rich phase in Al-5wt.%Fe-5wt.%Si alloys was granulated; the phase transformation from metastable platelet Al3 FeSi and blocky Al8Fe2 Si to stable Al5 FeSi had occurred. With the extension of heat treatment, the Si phase coarsened gradually.
