Improvement of tribo-mechanical properties of directionally solidified CM-247 LC nickel-based super alloy through laser material processing

Nickel-based super alloy was used in high mechanical stress applications due to their good creep resistance and oxidation behaviour. However, their undesirable tribological behaviour is the main technical issues in several applications. In this study, nickel-based super alloy CM-247 LC was laser processed in order to improve the tribo-mechanical properties. The metallurgical study was performed using optical microscopy (OM), scanning electron microscopy (SEM) with electron dispersive spectroscopy (EDS) and X-ray diffraction analysis (XRD). The optimized laser parameter shows a significant grain refinement with finely dispersed cell-like structure which enhanced the hardness up to 466 HV_0.3. The laser-melted regions were showing with subtle variations in the distribution and shape of γ′ precipitates. XRD spectra were dominated from the γ and γ′ peaks. The maximum weaker reflections were consistent with the occurrence of MC carbides. The wear rates of laser-processed sample were reduced significantly while compared with substrate sample. The examined worn surface specifies that adhesion and abrasion was a significant wear. The phases like γ′ morphology, γ-γ′ eutectics and sizes can influence the tribological behaviour.