【摘要】 研究了锗在熔融玻璃包覆下循环过热后的过冷度及凝固组织特征。结果发现:锗在熔融玻璃包覆下循环过热后可获得312 K的过冷度,熔融玻璃的成分是影响锗过冷度的主要因素,要使锗获得深过冷,熔融玻璃中必需含有一定量的碱性氧化物。过冷度不仅影响锗凝固后晶粒的尺寸,而且也影响晶粒的形貌。过冷度等于或小于90 K,晶粒比较粗大,晶界平直、棱角分明,表现出小平面生长的特征;过冷度大于90 K时,晶界圆滑、没有明显棱角,表现出非小平面生长的特征。在过冷度为90~180 K时,组织由纵向和横向尺寸有明显差别的长枝晶和细小的等轴晶组成;过冷度大于180 K后,组织为均匀细小的等轴晶。更多还原

【Abstract】 The undercooling of germanium superheated under the slag consisting of soda-lime glass and B₂O₃ and its structure after nucleation have been studied in this paper.It is found that germanium can be undercooled to a degree as high as 312 K by superheating it under the slag consisting of soda-lime glass and B₂O₃.The undercooling of germanium mainly depends on the composition of the slag.In order to make germanium highly undercooled,the slag must contain a certain amount of alkaline oxides.The undercooling influences not only the grain size,but also the grain morphology of germanium.When the undercooling is lower than 90 K,the structure consists of large plates with pronounced edges,which shows the behavior of lateral growth.When the undercooling is high than 90 K,the crystal interface transforms to smooth curves from sharp straight lines,which shows the behavior of continuous growth.In an undercooling region from 90 K to 180 K,the structure consists of large dendrites and small grains.The structure becomes to be homogenous refined grains when the undercooling is higher than 180 K.更多还原