High-intensity chromium ion implantation into Zr-1Nb alloy

High-intensity low energy chromium ions implantation was used for surface modification of zirconium Zr-1Nb alloy. The Cr ions were extracted from cathodic arc plasma and focused ballistically using a negatively biased hemispherical grid electrode immersed in plasma. The microstructure, phase composition and elemental distribution of Cr-implanted alloy were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX), respectively. The results revealed the formation of ZrCr₂ Laves phase of C15 polytype after Cr ions implantation. The content of Laves phase increases with implantation temperature up to 22 vol% (at 900 °C). The Laves phase precipitations are nucleated and grew alternately inside the α-Zr solid solution matrix. The high-temperature (HT) oxidation resistance of Cr-implanted samples was analyzed during HT oxidation test in steam at 1000 and 1200 °C for 10 min.