ABSTRACT The influence of green density between 6.5 and 7.3 g cm−3 on the anisothermal and isothermal shrinkage of atomized plain iron was investigated by dilatometry. The geometrical activity deriving from the extension of the interparticle contact areas and the structural activity provided by the defectiveness of the interparticle contacts promote anisotropic anisothermal shrinkage starting from 500°C up to the bcc to fcc iron transformation. It displays a minimum at 6.9 g cm−3, resulting from the combined effects of the thermodynamic driving force and of geometrical and structural activity. Anisothermal shrinkage is caused by an anisotropic increase in the internal radius of the neck. Anisotropic isothermal shrinkage is smaller than the anisothermal one and is almost independent on green density. No anisothermal shrinkage was observed on the tapped powder, demonstrating that anisothermal shrinkage in green specimens is due to geometrical and to structural activity introduced by prior cold compaction.

中文翻译：

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生坯密度对素铁生坯件等温收缩和等温收缩影响的膨胀学研究

摘要 通过膨胀法研究了 6.5 和 7.3 g cm−3 之间的生坯密度对雾化素铁的等温收缩和等温收缩的影响。源自颗粒间接触面积扩展的几何活动和由颗粒间接触缺陷提供的结构活动促进了从 500°C 开始的各向异性各向异性收缩，直至 bcc 到 fcc 铁的转变。它显示出最小值为 6.9 g cm−3，这是由于热力学驱动力以及几何和结构活动的综合影响。各向异性收缩是由颈部内半径的各向异性增加引起的。各向异性等温收缩小于各向异性等温收缩，几乎与生坯密度无关。