Investigation of structural relaxation by hydrogen absorption in ball-milled alloys

Hydrogen absorption is shown to be an excellent probe for studying structure and relaxation of nanocrystalline materials prepared by ball-milling. Grain boundaries in nanocrystalline FeTi have a highly disordered (amorphous-like) character, in contrast to nano-materials prepared by gas condensation methods,. Effects of relaxation on pressure-concentration isotherms are discussed in terms of densification, strain reduction and chemical ordering in ball-milled materials, both amorphous and nanocrystalline, These studies were previously inaccessible, because of the need for activation (high temperature annealing) preceding hydrogenation, which is now eliminated by addition of a catalyst.