首页|Surface strengthening and self-lubrication enhancement of CoCrNi medium-entropy alloy by powder-pack boronizing
Surface strengthening and self-lubrication enhancement of CoCrNi medium-entropy alloy by powder-pack boronizing
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NSTL
Elsevier
The CoCrNi medium-entropy alloy (MEA) exhibits an impressive ductility, but its low hardness (～352 HV) and poor wear resistance limit its engineering applications. In this study, a significant increase of surface hardness and enhancement of self-lubrication were achieved for the CoCrNi MEA using powder-pack boronizing. Results indicate that dual reaction layers with a total thickness of about 50 μm were formed on the surface. These two strengthened layers are mainly consisted of silicide (Ni2Si) and borides (CoB, Cr5B3). The hardness of the affected region reaches to 11-21 GPa dependence on the cross-sectional depth, being about 6 times higher than that of untreated MEA. In the deionized water condition, the friction and wear rate reductions of the boronizing treated specimen reach to about 25% and 63%, respectively. Energy Dispersive Spectrometer (EDS) and X-ray Photoelectron Spectroscopy (XPS) analysis on the wear scars showed that a silicon/boron-containing tribofilm was formed under the water environment, which reduces the friction coefficient and enhances the wear resistance. Our study demonstrates that powder-pack boronizing is a powerful way to enhance surface hardness and selflubrication properties of CoCrNi MEA.
NSTL
Elsevier
