Intermetallic Phase Transformations during Low-Temperature Heat Treatment of Al/Ni Nanoparticles Synthesized within Thermally Evaporated Fatty Acid Films

The phase evolution during low-temperature heat treatment of Al and Ni nanoparticles synthesized within thermally evaporated fatty acid films is described. Nanoparticles of aluminum and nickel were grown in thermally evaporated stearic acid (StA) films by immersion of the film sequentially in solutions containing Al 3+ and Ni 2+ ions followed by in-situ reduction of the metal ions to yield nanoparticles of Al and Ni of ca. 230 Å diameter within the fatty acid matrix. Thermal treatment of the StA − (Al + Ni) nanocomposite film at 100 °C resulted in the formation of a metastable η phase, Al 9 Ni 2, which on further heating at 125 °C decomposed to form Al 3 Ni 2 .