Eutectic modification of A356 alloy with Li addition was investigated with scanning electron microscopy （SEM） and differential scanning calorimetry （DSC）. SEM micrograph results indicate that the transition of eut...Eutectic modification of A356 alloy with Li addition was investigated with scanning electron microscopy （SEM） and differential scanning calorimetry （DSC）. SEM micrograph results indicate that the transition of eutectic morphology, which is changed from flake-like to fibrous, is dramatically induced with the addition of 0.3% （mass fraction） Li. The larger microhardness corresponds to the modification morphology of the eutectic phase for A356 alloy with 0.3% Li addition. The modification effect is increased with increasing the cooling rate and degraded with prolonging the holding time of temperature. DSC results show that the eutectic solidification temperature of A356 alloy with Li addition is decreased and the eutectic temperature depression with 0.3% Li addition is decreased by 2.9 °C in cast-iron mold. The mixing enthalpies of Li with Si and Al in A356 alloy, which were calculated by the Miedema model, were used to study the mechanism of modification and ascertained its restricted growth theory.展开更多
In this study, we investigate the fabrication of periodically poled lithium niobate(PPLN) microdisk cavities on a chip. These resonators are fabricated from a PPLN film with a 16 μm poling period on insulator using c...In this study, we investigate the fabrication of periodically poled lithium niobate(PPLN) microdisk cavities on a chip. These resonators are fabricated from a PPLN film with a 16 μm poling period on insulator using conventional microfabrication techniques.The quality factor of the PPLN microdisk resonators with a 40-μm radius and a 700-nm thickness is 6.7×10~5. Second harmonic generation(SHG) with an efficiency of 2.2×10^(-6) mW(-1) is demonstrated in the fabricated PPLN microdisks. The nonlinear conversion efficiency could be considerably enhanced by optimizing the period and pattern of the poled structure and by improving the cavity quality factors.展开更多
基金Project (42-QP-009) supported by the Research Fund of the State Key Laboratory of Solidification Processing, ChinaProject (JC200929) supported by the Fundamental Research Fund of Northwestern Polytechnical University, ChinaProject (B08040) supported by the 111 Project of China
文摘Eutectic modification of A356 alloy with Li addition was investigated with scanning electron microscopy （SEM） and differential scanning calorimetry （DSC）. SEM micrograph results indicate that the transition of eutectic morphology, which is changed from flake-like to fibrous, is dramatically induced with the addition of 0.3% （mass fraction） Li. The larger microhardness corresponds to the modification morphology of the eutectic phase for A356 alloy with 0.3% Li addition. The modification effect is increased with increasing the cooling rate and degraded with prolonging the holding time of temperature. DSC results show that the eutectic solidification temperature of A356 alloy with Li addition is decreased and the eutectic temperature depression with 0.3% Li addition is decreased by 2.9 °C in cast-iron mold. The mixing enthalpies of Li with Si and Al in A356 alloy, which were calculated by the Miedema model, were used to study the mechanism of modification and ascertained its restricted growth theory.
基金supported by the National Natural Science Foundation of China(Grant Nos.11734009,11674181,11774182,and 11674184)the 111 Project(Grant No.B07013)+1 种基金PCSIRT(Grant No.IRT 13R29)CAS Interdisciplinary Innovation Team
文摘In this study, we investigate the fabrication of periodically poled lithium niobate(PPLN) microdisk cavities on a chip. These resonators are fabricated from a PPLN film with a 16 μm poling period on insulator using conventional microfabrication techniques.The quality factor of the PPLN microdisk resonators with a 40-μm radius and a 700-nm thickness is 6.7×10~5. Second harmonic generation(SHG) with an efficiency of 2.2×10^(-6) mW(-1) is demonstrated in the fabricated PPLN microdisks. The nonlinear conversion efficiency could be considerably enhanced by optimizing the period and pattern of the poled structure and by improving the cavity quality factors.
