Stress and TEM measurements as a function of temperature for aluminum alloys

Measurements of the stress in situ as a function of temperature have proven to be an easy and powerful technique for obtaining information on the temperature and time for formation of both solid-state reactions and changes in morphology and structure. Correlating these changes using hot-stage transmission electron microscopy (TEM) and X-ray diffraction measurements has demonstrated that the stress changes correspond to chemical reactions and structural changes. The solid-state reactions of films consisting of aluminum with tantalum and vanadium were examined using stress measurements, TEM, X-ray diffraction, resistivity, and surface roughness measurements. The growth of very large gains (50-100 μm) in Al/Cu/Cr films was also examined using both stress measurements and hot-stage TEM in situ during thermal cycling. Stress measurements revealed that aluminum reacts with vanadium first at 370°C and then at 410°C. Using X-ray diffraction and cross-sectional TEM analysis, the first reaction was found to correlate with the formation of VAl₃ and the second reaction with the formation VAl₁₁. The thickness of the vanadium aluminide layer changed significantly after the second reaction. Similar measurements of Al-Si/Ta revealed that an untextured jagged TaAl₃ layer forms at 430°C