Metastable nanostructures with enhanced hardness of Ti-Ni-Al alloy through electrostatic levitation processing

We prepared a Ti-Ni-Al alloy comprised of metastable equiaxed (beta Ti) dendrites and interdendritic Ti2Ni phase by means of electrostatic levitation plus quenching. It exhibited an impressive improvement in hardness compared with the sample through DTA processing. By employing the double Cs corrector transmission electron microscope characterization, the coherent solute cluster and semi-coherent nano-distortion (beta Ti) were found to form within the metastable (beta Ti) dendrites, and (alpha Ti) nanoprecipitates generated inside interdendritic Ti2Ni phase matrix. These dispersive metastable nanostructures and the novel (alpha Ti) + Ti2Ni biphase boundary contributed cooperatively to pinning dislocation. The harmonic cooperation of precipitation strengthening, solution strengthening and fine-grained strengthening were realized to enhance the alloy.