Kirkendall porosity during thermal treatment of Mo–Cu nanomultilayers

Mo–Cu nanomultilayers were investigated as part of an effort to understand mechanisms of thermal stability in layered nanostructures. The multilayers were fabricated by magnetron sputtering with a range of layer spacings. Thermal treatment of the Mo–Cu nanomultilayers showed the formation of nanovoids along Cu–Mo layer interfaces and Mo–Mo grain boundaries. The size of the void was concurrent with the size of Cu. This was attributed to a Kirkendall type of effect caused by vacancy diffusion in metallic nanoscaled multilayered films.