Phase evolution in a Cu-18 at.% Li alloy as a function of temperature under different atmospheres.

Scanning electron microscopy (SEM), neutron diffraction (ND) and thermal analysis studies were used to check the behaviour of powders of Cu-18 at.% Li alloy in the temperature range between room temperature and 973 K under different types of atmospheres. After heating at 973 K the remaining lithium Content is about 15 at.% and 13 at.%, in the tests under argon and vacuum, respectively.In contrast, if the sample is heated in air or in nitrogen, the lithium content in solid solution in the alloy at temperatures of about 873 K is very low (3 at.%). Consequently the alloy is in solid state at temperature as high as 1273 K. The heating of the alloy powders in nitrogen and in air, at atmospheric pressures, leads to the growth of lithium nitride, which was not expected. (c) 2005 Elsevier B.V. All rights reserved.