【摘要】 用定向凝固装置,研究铸铁熔体的衰退及石墨形态的转变。对石墨形态连续衰变过程的观察,发现了以前从未报导过的蠕虫状向过冷石墨转变的分界线。这表明石墨生长机制在分界线处发生了突变。本文认为铸铁熔体衰退过程中,石墨形态经历了如下转变:球状→蠕虫状→D 型片状→A 型片状,石墨晶体生长机制发生了渐变→突变→再渐变的过程。其中球状石墨→蠕虫状石墨的转变是渐变;蠕虫状石墨→过冷石墨的转变是突变;过冷石墨→A 型片状石墨的转变是再一次渐变。更多还原

【Abstract】 By means of the technique of LMC directional solidification,the fading of cast iron melt and the transition of graphite morphology were studied,When the continuous fading process of graphite morphology was observed,the boundary of the transition from the vermicular to the under-cooled graphite was found,which had been never reported before,This phenomenon shows that a sudden transition of the growth mechanisms of graphite has occured at the boundary,It is consi- dered that in the fading process of cast iron melt the graphite morphology has gone through the following transitions,the spheroidal--the vermicular--the type D flake,and at the same time a series of changes are taking place,a slow transition,a sudden transition,and then again a slow transition.Among them the transition from the spheroidal to the vermicular is a slow transition,that from the vermicular to the undercooled type is D flake is sudden transition;and that from the undercooled type D flake to the type A fl ake again a slow transition.更多还原