自支撑Mg靶膜的制备

用真空蒸发法成功制备了１７００～１９６１ μｇ／ｃｍ ２ 的薄自支撑 Ｍ ｇ 靶膜和９０～９５ μｍ 的厚自支撑 Ｍ ｇ 靶膜。甜菜碱是制备 Ｍｇ 靶膜有效的解离剂。讨论了真空蒸发制靶过程中的主要技术难点。

同位素Mg靶的制备

文章介绍２４ＭｇＯ转换成金属小球的还原技术以及同位素Ｍｇ靶的３种制备方法，即滚轧法、电阻加热法和聚焦重离子溅射法。滚轧法适用于制备＞０．１５ｍｇ／ｃｍ２的自支撑２４Ｍｇ靶，而后２种方法主要用来制作有衬底靶。

BRISOL钠同位素放射性核束的产生

北京放射性核束装置在线同位素分离器(BRISOL)采用100 MeV、200μA回旋加速器提供的质子束打靶产生中、短寿命放射性核束,在线分析后供物理用户使用,其质量分辨率好于20000。为开展20 Na核的奇异衰变特性研究,研制了氧化镁靶,并采用100 MeV质子束轰击氧化镁靶在线产生了20~26 Na^+的钠同位素放射性核束。当质子束流强为8μA时,20 Na^+离子束的最大产额为2×10^5 s^-1,21 Na^+离子束的最大产额为4×10^8 s^-1。完成了北京放射性核束装置首个放射性核束物理实验,累计供束近200 h。

Effect of heat input on microstructure and mechanical properties of butt-welded dissimilar magnesium alloys joint

The effects of heat input on the microstructures and mechanical properties of tungsten inert gas （TIG） butt-welded AZ31/MB3 dissimilar Mg alloys joint were investigated by microstructural observations, microhardness testing and tensile testing. The results reveal that with the increase of heat input, the width of welding seam increases obviously and the grains both in the fusion zone and the heat affected zone coarsen during TIG welding process. The tensile strength of butt-welded joint increases with the increase of heat input and the maximum joining strength of 242 MPa is obtained with wedding current of 90 A. However, lots of welding pores occur with the further increase of heat input, which results in the decrease of joining strength. It is experimentally demonstrated that robust joint can be obtained by TIG welding process.