合成时间对Na_8Al_6Si_6O_(24)Cl_2:5%Eu^(3+),5%Tb^(3+)发光强度的影响

采用高温固相法合成Na_8Al_6Si_6O_(24)Cl_2:5%Eu^(3+),5%Tb^(3+)发光材料,研究不同合成时间对该材料发光强度的影响。XRD结果显示,稀土离子掺杂时,3-6h范围内合成时间的变化对方钠石晶体结构没有影响。在256 nm光激发下,测不同合成时间下的发射光谱,可以观察到随着合成时间的增加,发光强度逐渐增强,到达5h时,616 nm对应的5D0→7F2跃迁最大,发光强度最强。此时样品颜色相应的色坐标值为(0.6309,0.3382),色纯度为90.8%,相对亮度为99.93%。之后随着合成时间的增加反而逐渐减弱。

Influence of elevated Fe,Ni and Cr levels on tensile properties of SSM-HPDC Al-Si-Mg alloy F357

The microstructures and tensile properties of semi-solid metal high pressure die cast(SSM-HPDC) F357 alloys with low and high levels of Fe,Ni and Cr were compared in different temper conditions.ThermoCalc software was used to predict the different intermetallics that can be expected in the alloys,and scanning electron microscopy(SEM) with energy dispersive spectroscopy(EDS) was used to investigate the actual intermetallics that formed.The influence of these intermetallics on tensile properties was quantified.The results show that lower strength is obtained in the alloy with high Fe,Ni and Cr levels.This is attributed mainly to the formation of more π-Al8FeMg3Si6 phase,which removes strengthening Mg atoms from solid solution.Also,the ductility of the high Fe,Ni and Cr levels alloy is decreased significantly due to microcracking of the higher volume fraction π-Al8FeMg3Si6 and Al9FeNi phases.The combination of lower strength and ductility results in a decrease of the quality index of this alloy compared with the alloy with low levels of Fe,Ni and Cr.