The effect of trace additions of tellurium on oxidation and some other properties of aluminium-lithium base alloys

Abstract

Alloys of various chemical compositions with and without tellurium (Te) have been prepared in this research. Several types of tests were carried out, namely, tensile, ageing (hardness versus ageing time), erosion-corrosion, and oxidation, in addition to the evaluation of oxidation resistance by thermal shock. X-ray diffraction was also used to analyse the oxidation scales built on the samples. The microstructures of the alloys and oxides have been studied as well. It was found that the addition of small amounts (0.2 and 0.4 wt %) of Te led to drastic increases in oxidation resistance compared to the corresponding Te free alloy at both testing temperatures (300 and 500 °C). The great increase in resistance to environmental attack displayed by Te containing alloys was due to impediment of the interaction of Li with oxygen and enhancement of oxide plasticity and adhesion. Oxides grown on Te containing alloys remained intact when subjected to thermal shock. Te containing alloys also showed a great improvement in corrosion-erosion resistance compared to the other investigated Te free alloy. It was also noticed that Te enhanced the ductility of the base alloys themselves.