1996 年 47 巻 9 号 p. 784-789
In this study, transmission electron microscopy (TEM) was used to characterize the microstructures of as-sprayed, solution-treated, aged CoNiCrAlYTa coatings. The micro-vickers hardness test was used to estimate age hardening of the coatings. The hardness of as-sprayed coatings was about 590Hv. Hardness was decreased to about 560Hv in solution treatment at 1373K for 4 hours. It was increased, however, by aging at 1073K and 1173K after solution treatment.
TEM observation showed that the average grain size was about 0.5μm. The γ and β-phases coexisted in as-sprayed coatings. Solution treatment at 1373K coarsened the grain size to about 1.5μm. Wedge-shaped β precipitates in the γ-phase were produced by aging. Needle-shaped α-Co and massive σ precipitates in β phase were clearly produced by aging. These precipitations are therefore thought to contribute to age hardening.