Behaviour of NaK2–graphite powders at various pressures Original Research Article

Four samples of graphite–NaK2 were studied under pressure: NaK2+9C (the maximal alloy content before agglomeration of the powder when starting with 40-μm graphite powders), NaK2+12C (which corresponds to MC4 superdense phase composition) and NaK2+20C (with enough metal to form MC8, but not enough to prepare KC8). Two NaK2+20C samples were studied: as prepared or after moderate heating (200°C for 2 days) since DSC measurements depend on their heat treatment. The increase of pressure from ambient pressure to 25 kbar involves an extra-intercalation but the initial composition and history influence largely the behaviour of the powders.