3D morphological evolution of porous titanium by x-ray micro- and nano-tomography

The 3D morphological evolution of titanium foams as they undergo a two-step fabrication process is quantitatively characterized through x-ray micro- and nano-tomography. In the first process step, a Cu-Ti-Cr-Zr prealloy is immersed in liquid Mg, where Cu is alloyed with Mg while a skeleton of crystalline Ti-Cr-Zr is created. In the second step, the Mg-Cu phase is etched in acid, leaving a Ti-Cr-Zr foam with submicron struts. 3D images of these solidified Ti-Cr-Zr/Mg-Cu composites and leached Ti-Cr-Zr foams are acquired after 5, 10, and 30 min exposure to liquid Mg. As the Mg exposure time increases, the Ti-Cr-Zr ligaments grow in size. The tortuosity loosely follows the Bruggeman relation. The interfacial surface distribution of these Ti-foams is qualitatively similar to other nano-porous metal prepared by one-step dealloying. The characteristic length of the Mg-Cu phase and pores are also reported.