Effect of P-Na united modification on Al-22%Si-1.0%Cu-0.5%Mg-0.5%Mn alloy was studied. The results show that the refining effect of P-Na addition on primary silicon is superior to that of P and the former could modify...Effect of P-Na united modification on Al-22%Si-1.0%Cu-0.5%Mg-0.5%Mn alloy was studied. The results show that the refining effect of P-Na addition on primary silicon is superior to that of P and the former could modify eutectic silicon at the same time. Effects of P-Na modification on crystallization and microstructure of hypereutectic Al-Si alloys were studied with Electron-Scanning Microscope, Electron-Probe and X-ray diffractometer. The modification mechanism represents that on one hand, the primary silicon is refined by AlP as heterogeneous nucleus; on the other hand, when Na is added at the same time, P atoms are difficult to diffuse in the melt, and then enrichs on the growing faces of silicon phase. Moreover, a SiP compound was also discovered in Si crystals, which prevents the growth of silicon phase and refines the primary silicon.展开更多
通过对黑龙江龙凤山和青海瓦里关Brewer地基臭氧总量的长期观测资料以及与观测时段对应的全球NCEP R1系列位势高度再分析资料的统计分析发现,龙凤山和瓦里关臭氧总量观测值有时存在剧烈的逐日变化,对这种异常变化进行定量分析,并对其与...通过对黑龙江龙凤山和青海瓦里关Brewer地基臭氧总量的长期观测资料以及与观测时段对应的全球NCEP R1系列位势高度再分析资料的统计分析发现,龙凤山和瓦里关臭氧总量观测值有时存在剧烈的逐日变化,对这种异常变化进行定量分析,并对其与对流层天气过程的关系进行研究,发现两者之间存在良好的对应关系。臭氧总量的异常变化大多数出现在11月至次年5月的冬、春季节,并且臭氧总量的异常升高（第一类异值点）总是伴随着平流层低层（250-70 h Pa）的槽线和地面（1000 h Pa）的低压中心后方的天气形势,而臭氧总量的异常降低（第二类异值点）则时常伴随平流层低层的脊线和地面的高压中心后方的天气形势,这表明臭氧总量的异常变化可以作为地面天气系统转变的一个信号。展开更多
文摘Effect of P-Na united modification on Al-22%Si-1.0%Cu-0.5%Mg-0.5%Mn alloy was studied. The results show that the refining effect of P-Na addition on primary silicon is superior to that of P and the former could modify eutectic silicon at the same time. Effects of P-Na modification on crystallization and microstructure of hypereutectic Al-Si alloys were studied with Electron-Scanning Microscope, Electron-Probe and X-ray diffractometer. The modification mechanism represents that on one hand, the primary silicon is refined by AlP as heterogeneous nucleus; on the other hand, when Na is added at the same time, P atoms are difficult to diffuse in the melt, and then enrichs on the growing faces of silicon phase. Moreover, a SiP compound was also discovered in Si crystals, which prevents the growth of silicon phase and refines the primary silicon.
文摘通过对黑龙江龙凤山和青海瓦里关Brewer地基臭氧总量的长期观测资料以及与观测时段对应的全球NCEP R1系列位势高度再分析资料的统计分析发现,龙凤山和瓦里关臭氧总量观测值有时存在剧烈的逐日变化,对这种异常变化进行定量分析,并对其与对流层天气过程的关系进行研究,发现两者之间存在良好的对应关系。臭氧总量的异常变化大多数出现在11月至次年5月的冬、春季节,并且臭氧总量的异常升高（第一类异值点）总是伴随着平流层低层（250-70 h Pa）的槽线和地面（1000 h Pa）的低压中心后方的天气形势,而臭氧总量的异常降低（第二类异值点）则时常伴随平流层低层的脊线和地面的高压中心后方的天气形势,这表明臭氧总量的异常变化可以作为地面天气系统转变的一个信号。
