Nanocrystalline Ni-Cr-Y films reach 11.0 GPa hardness in doping study

A study of sputtered nanocrystalline nickel-chromium-yttrium films found that varying chromium and yttrium contents while holding grain size constant changed the alloy’s deformation behavior, with the strongest ternary composition reaching a hardness of 11.0 GPa. The authors described that value as among the highest reported for single-phase nanocrystalline nickel alloys with grain sizes near 20 nm, rather than as a record.

According to the study abstract, the experimental films were examined by nanoindentation to assess hardness. Chromium was added in solid solution to strengthen the lattice, while yttrium was observed to enrich the examined grain boundaries. The researchers systematically varied the alloying-element contents with grain size kept constant, allowing them to investigate how grain-interior and grain-boundary chemistry jointly affected mechanical response.

Chromium additions produced solid-solution strengthening, but the abstract reports that this effect saturated at higher concentrations as grain-boundary-dominated deformation processes emerged. Indentation pileups containing slip steps and grain rotation provided evidence for those processes. Increasing yttrium concentration strengthened the grain boundaries by pinning dislocations and suppressing dislocation emission, grain-boundary sliding and grain rotation. The authors associated a weakened chromium contribution at higher yttrium concentrations with a reduced dislocation-bowing distance caused by dopant pinning.

The findings are based on the published abstract; the supplied source does not provide the full article, so the report cannot assess the complete methods, underlying measurements or uncertainties. Within the stated scope of nanocrystalline Ni-Cr-Y sputtered films, the results indicate that controlling both grain and grain-boundary chemistry can influence deformation mechanisms and increase hardness. The authors present this tuning approach as a possible strategy for strengthening nanocrystalline metals, but the reported evidence concerns hardness measured by nanoindentation rather than a broader range of structural or engineering performance tests.

Subject of Research: Effects of chromium and yttrium doping on hardness and deformation mechanisms in nanocrystalline Ni-Cr-Y films

Article Title: Synergistic doping of the grain interior and grain boundary alters deformation mechanisms and enables extreme strength in nanocrystalline Ni-Cr-Y alloys

Article References: Liu, Y., Trelewicz, J. R., & Rupert, T. J. (2026). Synergistic doping of the grain interior and grain boundary alters deformation mechanisms and enables extreme strength in nanocrystalline Ni-Cr-Y alloys. Journal of Materials Science, 61(43), 34103-34123. https://doi.org/10.1007/s10853-026-13753-1

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13753-1

Keywords: nanocrystalline alloys, nickel-chromium-yttrium, grain boundaries, solid-solution strengthening, nanoindentation, hardness, yttrium segregation, chromium doping, deformation mechanisms, materials science, Synergistic, doping