Effect of Cr nanoparticle dispersions with various contents on the oxidation and phase transformation of alumina scale formation on Ni2Al3 coating

In this work, the NiCr nanocomposite films were fabricated with various contents of Cr nanoparticle dispersions and then subsequently aluminized to obtain the Cr nanoparticle-dispersed Ni2Al3 coating at temperature 620 °C. For comparison, the samples without Cr nanoparticle dispersions were prepared under the same experimental condition. The results showed that the Ni2Al3 coating with Cr nanoparticle dispersions has a lower oxidation rate than the Cr-free Ni2Al3 coating after oxidation. The result also indicates that Cr nanoparticle dispersions in the Ni2Al3 coating promoted the transformation of θ-into-α alumina phase and surface microstructure evolution based on the investigations of photo-stimulated luminescence spectroscopy (PSLS) and scanning electron microscopy (SEM), respectively. Furthermore, with increasing the content of Cr nanoparticle dispersions from 2.5 wt% to 5 wt% in the Ni2Al3 coatings can significantly reduce the oxidation rate through accelerated phase transformation of metastable to stable alumina. In addition, the Cr nanoparticles in Ni2Al3 not only mitigate the cavities formation at the interface, but also grow an adherent alumina scale on aluminide. •Successfully prepared the Cr nanoparticles-free and disperesed-Ni2Al3 coatings.•The PSLS result confirmed that the Cr dispersed-Ni2Al3 played a significant role in the phase transformation of θ-into-α alumina.•The oxidation resistance of Cr-dispersed Ni2Al3 improved through accelerated phase transformation of metastable to stable alumina.•The dispersion of Cr particles contents have good effect on oxidation and phase transformation of alumina on aluminide.