Pt₂Al₃ formation on evaporated and large‐grained Al substrates

The growth of Pt₂Al₃ during thermally induced Pt‐Al reaction is studied with two types of samples: bilayered thin films (Pt/Al) and Pt thin film on large‐grained Al substrate (Pt/<Al>). The same behavior upon vacuum furnace annealing is observed for both types of sample configurations: Pt₂Al₃ forms as the initial growing phase in a laterally uniform fashion, following a diffusionlimited process. A parabolic growth law of the form x² = kt is obtained in the temperature range 200 to 300 °C, where x is the thickness of the growing Pt₂Al₃ layer, t is the annealing duration, and the growth constant k is given by k = 1.02 × 10⁻² (cm²/s) exp ((−1.15 ± 0.1) eV/k_BT). The morphological rearrangements in the Al thin film during reaction is observed and discussed. The common Pt₂Al₃ growth kinetics on the two types of Al substrates suggests that neither the microstructure of nor the morphological rearrangements in the Al layer affect the Pt₂Al₃ growth significantly.