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The paper studies the influence of manganese ion implantation on the cavitation erosion behaviour of the
HIPed Stellite 6. The implantation process was conducted using implantation energy 175 keV, and the
fluences of implanted ions were set at 5 × 1016 Mn+/cm2 and 1 × 1017 Mn+/cm2. The microstructure of
the samples was investigated using scanning electron microscopy and X-ray diffraction. The cavitation
erosion tests were carried out according to the ASTM G32 standard with the stationary specimens
configuration. The cavitation erosion-damaged surfaces of unimplanted and implanted samples were
qualitatively investigated using scanning electron microscopy. Moreover, the phase development due to
the ion implantation and cavitation erosion was analysed using the X-ray diffraction technique. The
HIPed Stellite 6 microstructure is based on the cobalt-containing matrix consisting of γ (face-centred
cubic) and ε (hexagonal close-packed) crystal structures and Cr7C3 chromium carbides. Generally, the
applied implantation parameters have a minimal effect on the microstructure and erosion resistance.
The X-ray diffraction analysis shows a negligible effect of implantation on the microstructure. The
implantation using 1 × 1017 Mn+/cm2 seems the most promising for prolonging the cavitation erosion
incubation stage as well as for minimalizing the material loss (30.4 mg) and erosion rate (1.8 mg/h);
the unimplanted Stellite 6 shows these indicators at the comparable level of 34.5 mg and 2.0 mg/h,
respectively. The study confirmed that cavitation loads induce the face-centred cubic to hexagonal
close-packed phase transformation in the cobalt-based matrix. The cavitation erosion mechanism relies
on the material loss initiated at the carbides/matrix interfaces. Deterioration starts with the cobalt
matrix plastic deformation, weakening the restraint of Cr7C3 carbides in the metallic matrix. First,
the deformed cobalt matrix and then hard carbides are removed at the interfaces. Further, the cobalt-
based matrix undergoes cracking, accelerating material removal, pits formation, and craters growth.
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