Microstructural evolution and phase analysis of SS410–Al2O3–SiC multilayered functionally graded composite fabricated through laser cladding

Abstract

In the present study, a functionally graded metal-ceramic composite structure comprising SS410, Al2O3, and SiC particles with varying composition, structure and properties in a single deposit was successfully fabricated using direct energy deposition (DED). The composition varied from 90 % SS410 with 10 % (xAl2O3 + ySiC) to 10 % SS410 with 90 % (xAl2O3 + ySiC), where x = 70 % and y = 30 % in a five-layered FGM design. The microstructure, phase evolution and mechanical properties of the components with different composition gradients were characterized by microscopy, energy dispersive spectroscopy, wavelength dispersive spectroscopy, X-ray diffraction and micro hardness. The investigation revealed that complex phases such as C0.12Fe0.79Si0.09, M7C3, Fe3C, and Fe3Si formed as a result of the interaction between SiC and SS410 during the cladding process. Microstructural analysis showed a transition from columnar dendrites at the bottom zone of the cladding to a typical cellular structure and carbide particle agglomerates in the middle zone, with finer grains at the top zone. This gradation in microstructure correlated with an increase in microhardness ranging from 299 HV at the bottom to 966 HV at the top. This enhancement in hardness is primarily attributed to solid solution strengthening from C and Si originating from the decomposition of SiC and the precipitation of intermetallic phases.