Scripta Materialia 235 (2023) 115594

Ultrahigh strength-ductility of nanocrystalline Cr₂AlC coating under micropillar compression

Jianghuai Yuan, Shenghao Zhou, Haichen Wu, Zhenyu Wang*, Yan Zhang, Guangxue Zhou, Guanshui Ma, Peiling Ke, Aiying Wang*

MAX phases gain increasing attention as protective coatings due to superior anti-corrosion and oxidation resistance for harsh high-temperature applications. However, the lower strength and strength-ductility trade-off in bulk MAX phases still pose an enormous challenge arising from the large ratio of c/a lattice parameters and less activated slips. Here, nanocrystalline Cr₂AlC coating with high-purity was fabricated using a hybrid arc/ sputtering technique with subsequent thermal annealing. Cylindrical micropillar compression test was conducted by FIB milling to identify the mechanical properties of the coating under deformation. The stress-strain curves demonstrated that an ultrahigh compressive strength of 5.3 GPa with strain beyond 12.5% was surprisingly achieved for Cr₂AlC coating, which was 5 times larger than all the reported bulk MAX phases before. Specifically, the extraordinary ductility at RT is ascribed to the synergy of the fundamental basal slip, additional non-basal slip and deformation twinning stimulated by ultra-refinement effect of nano-crystalline Cr₂AlC coating.   

URL：https://doi.org/10.1016/j.scriptamat.2023.115594