Evolution of Metallic Foams Using Hot-stage Microscopy

Hot-stage microscopy (HSM) - a technique widely used in material sciences - coupled with commercial image analysis software is proposed as an alternative and simple approach for quantifying the foaming kinetics during the formation of metallic foams by the powder metallurgical (PM) method. The foaming process is performed inside the hot-stage microscope. The sample of small dimensions is continuously monitored by a TV camera and its shape is recorded on a videotape. The captured HSM images are analysed by image-analysis procedures to obtain the expansion curve of the sample from the variation of its projected area. Apart from the expansion curves, this technique also enables observing the thermal events occurring onto the external surface skin of the foams detecting coalescence events that could provoke structural imperfections.