Mechanical milling of Fe–Li and Cu–Li systems and their nitrogen absorption properties

It is known that lithium reacts with nitrogen to produce nitride at room temperature. Lithium alloys are one of the candidates for nitrogen absorption materials. On the other hand, it is also known that the mechanical milling is generally used to create various non-equilibrium alloys, which are usually in active powder forms. In this work, in order to activate the nitrogen absorption properties of lithium, the mechanical milling of lithium systems is performed. As the alloying elements, iron and copper are chosen, since both systems of Fe–Li and Cu–Li have no intermediate phase in equilibrium. For mechanically alloyed powders, the atomic structure and the reactivity with nitrogen are investigated using X-ray diffractometry, thermal analysis, etc. In the case of Fe–Li, the mechanically milled sample shows high reactivity with nitrogen for a short milling time, compared with lithium in bulk form. While, Cu–Li forms supersaturated solid solution which hardly reacts with nitrogen at room temperature.