An investigation of the effect of processing conditions on the microstructure of vacuum plasma-sprayed Ti–Zr–Ni quasicrystal coatings

Ti41.5Zr41.5Ni17 (at.%) powders from two batches having different size fractions have been vacuum plasma sprayed to form coatings using different sets of spray parameters. The powders are composed mainly of the HCP alpha and Laves phases which transform to i-phase owing to rapid quenching during plasma spraying. The coatings are examined using image analysis, hardness tester, XRD, SEM, and TEM. TEM studies revealed that the coating has a microstructure constituted by extremely fine grains. It has been observed that the polycrystalline to i-phase transformation occurs in both coatings irrespective of the differences in starting powder size and other spray parameters.