Preparation of a 6Li0.74Mg0.26 alloy target

For a neutron-lifetime experiment at the National Institute of Standards and Technology (NIST), an alloy of 6Li and Mg was prepared as a disk 2.8 mm thick and 37.9 mm in diameter. Three-plus grams of a homogeneous alloy with a 6Li content approaching 74 at%, a very low hydrogen content and a low oxygen content were required. A sealed stainless-steel crucible was used for the alloying, in consideration of the chemical activities and vapor pressures of Li and Mg at the alloy-formation temperature (≥925 K). This report includes design details of the weld-sealed crucible, adaptations made to a radio-frequency (RF) induction furnance and the process used to prepare 4.5 g of the alloy, recover the alloy from the crucible and shape it into a disk. For ten months, the disk was stored successfully by continous vacuum pumping at 1.3 kPa. Back-scattered gamma rays revealed the alloy had acceptably low levels of hydrogen and oxygen. No other contaminants were detected.