High-speed video analyzes microcracking during additive manufacturing of tungsten

Abstract

Most of our day-to-day encounters with tungsten metal are limited to seeing its glowing coils in outdated incandescent light bulbs. However, the exceptional thermal conductivity and excellent radiation shielding properties of this very dense metal suggest that it is ideally suited to use as a plasma facing material in containment systems in emerging fusion reactors. In order for that to happen, however, researchers must overcome a critical roadblock. When tungsten cools down—from either high-temperature processing or after use in extreme environments—it stops being ductile and becomes brittle. In turn, the material develops microcracks and loses its strength. This is particularly problematic for the additive manufacturing of tungsten components, which uses laser heating to melt this metal and conform it to custom curvatures and shapes. Moreover, while researchers have examined failed tungsten articles and analyzed the networks of fractures that had formed, postmortem analyses have not provided much insight into the mechanisms that drive microcrack formation.