Abstract
Recent advancements have shown the effectiveness of strengthening 316L with TiC particles addition through the laser powder bed fusion(LPBF)process.However,the question remains whether TiC under-goes decomposition into Ti and C atoms,primarily because of the challenges associated with measuring C at low concentrations.In this study,we employed atom probe tomography(APT)to provide evidence of decomposition by observing the presence of Ti and C atoms in the 316L matrix.The fast cooling rate of the LPBF process results in the supersaturation of Ti and C in the 316L matrix.Adding 3 wt％TiC particles increased the yield strength of LPBF-processed 316L from 599 MPa to 832 MPa.The subsequent annealing treatment resulted in the formation of more TiC nanoparticles as a result of precipitation from the super-saturated Ti and C in the 316L matrix.Consequently,the yield strength was further enhanced to 959 MPa after annealing at 700 ℃ for 1 h.This study marks the first direct demonstration of the decomposition of TiC in metal matrix composites.
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