Insights into the exceptional cavitation erosion resistance of laser surface melted Ni-WC composites: The effects of WC morphology and distribution

Abstract

Laser surface melted (LSM) Ni-WC(-CeO2) composites with excellent cavitation erosion resistance (CER) were developed. The results showed that the CeO2 content could affect the morphology and distribution of the WC grains, the Ni grain size, and the CER of the LSM samples. Nevertheless, the addition of CeO2 could not guarantee the improvement of CER, as the SEM observation demonstrated that the CER of the LSM Ni-WC(-CeO2) samples were predominated by the morphology and distribution of WC. Only the samples that possessed a continuous Ni-WC eutectic with hierarchically arranged WC lamellae exhibited the best cavitation erosion resistance. Numerical simulation was performed to explore the effects of WC morphology and distribution on the CER from a perspective of the stress evolution and the energy change in response to a cavitation impact. This study suggested that the morphology and distribution of the hard strengthening phases could be the primary concern when designing cavitation erosion resistant material containing ductile and hard phases.