Multilayer samples of tantalum and aluminum with the composition of Al-25Ta were prepared by cold rolling of elemental foils. The microstructure and phases were characterized by XRD, SEM and TEM/SAED and the reactive phase formation was examinedby DSC and DTA measurements in multilayer foils rolled for different deformation levels. The rolling procedure yields a decrease of the Ta particle size in the Al matrix and also results In the formation of a multilayer structure with a thickness of theelemental foils down to 200 nm in average. No phase formation is observed during the cold rolling procedure. While XRD and DSC measurements show no phase formation up to the melting of aluminum for samples rolled up to 40 F&R (fold and rolling) passes, in samples rolled for 50 or more F&R passes a first phase formation reaction yield an interfacial layer of TaAl{sub}3. Contrary to former studies in the investigated cold rolled Al-25Ta multilayers the reaction starts at temperatures as low as about 340°C.The first stages of the reaction are associated with two exothermic maxima, that increase in amplitude and shift to lower temperatures with increasing number of F&R passes. At higher temperature the TaAl{sub}3 reaction layer thickens very sluggishly andyields a third exothermic maxima at about 600°C. Isothermal DSC scans show the reaction is not finished for samples containing elemental particles larger than 1μm after annealing at 550°C for 5h. In all the investigated samples no AlTa phase other thanTaAl{sub}3 was observed to grow for heat treatments up to 800°C. Multilayer samples heated up to 1400°C show a morphology consisting of small AlTa{sub}2 particles embedded In a single phase TaAl{sub}3 matrix. The multilayer microstructure and reactionproduct morphology are characterized by SEM and TEM investigations in cross-section and plan view geometry.
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