Correlation of Dynamic Elastic Properties of a Heat-Treated CoNiAl Alloy System with Its Microstructural Changes

Elastic responses of a solid represent structural properties and their changes as a function of external parameters like heat treatment. Heat treatment is a standard way to suitably alter the physical properties of an alloy. Here the effects of different annealing temperatures on polycrystalline Co–Ni–Al (Co₃₆Ni₃₆Al₂₈) samples were investigated in detail using X-ray diffraction and electron microscopy that showed significant changes in the phase fractions, B2 austenite (β), non-FSMA A1 (γ), and the Martensite L1₀\((\beta^{\prime})\) at room temperature. These changes in turn affected the transition temperatures, electrical resistivity, and magnetic properties of the samples. Using a resonant ultrasonic spectrometer (RUS), the dynamic elastic properties of the samples were measured at room temperature, and the results were found to reflect the phase evaluations correctly. This is the first time that RUS measurements are reported in this alloy system. All these findings can be used to fine tune a sample for the desired application.