Research on the energy properties and the storage stability of Al–Si–Li ternary alloy powders

Abstract

To solve the problems of storage stability and compatibility of the Al–Li alloy powders, a series of Al–Si–Li alloy powders containing two-phase structure were prepared based on Al–Si–Li ternary phase diagram. The energy release, attenuation and compatibility of the Al–Si–Li alloy powders were studied by oxygen bomb calorimeter, XRD, SEM, TG-DSC and SIMS. As the content of the AlSiLi intermetallic compound phase increased, the measured mass combustion enthalpies increase before decreasing. When the proportion of the AlSiLi intermetallic compound phase is 20 wt.% (denoted as 20%-ASL), it has the maximum mass combustion enthalpy (31729 J⋅g−1) which is higher than the theoretical mass enthalpy of the pure aluminum powder (31000 J⋅g−1). The aging test of the 20%-ASL alloy powder show that its measured mass combustion enthalpy only decreased by 5.5 % (from 31739 J⋅g−1 to 29921 J⋅g−1), along with the thermal oxidation weight gain decreasing from 95.82 % to 80.04 %, while mass combustion enthalpy of the Al–Li alloy powder with the same Li content decreased by 17.5 % (from 30325 J⋅g−1 to 25031 J⋅g−1), and the weight gain decreased from 96.68 % to 41.05 %. This indicates that the AlSiLi phase effectively improves the oxidation resistance and storage stability of the Al–Li alloy powders. To explain this, surface Li distribution of the 20%-ASL alloy powder was analyzed by SIMS. The results show that the AlSiLi phase can immobilize Li inside the particles to reduce surface Li content from 2.920 × 106 to 1.439 × 106 and improve its oxidation resistance, thereby improving its storage stability and compatibility.