Improving cavitation erosion resistance of laser-Clad Fe–Mn–Si–Cr–Ni shape memory alloy coatings through B alloying

This study addresses the issue of martensite phase generated by the iron-based "4D" printed coating on the surface of overcurrent components under cavitation stress tends to aggregate and coarsen, becoming a new source of cavitation damage. The investigation utilizes advanced characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM), to effects of boron(B) alloying on the microstructure and cavitation resistance of Fe-Mn-Si-Cr-Ni shape memory alloy coatings, as well as the associated strengthening mechanisms. The results show that the cavitation resistance of the coating initially improves and then decreases as the B content increases. The sample with the 0.5wt% B exhibited the best cavitation performance after 300 minutes of cavitation, with a cumulative mass loss of 0.16 mg, which was only 23.19% of the unalloyed sample. The addition of B elements does not hinder the martensite phase transformation, allowing the coating to continue mitigating cavitation stress via phase transformation. However, the formation of Cr 2 B phases effectively refines the austenite phase, promoting a uniform and fine martensite distribution after phase distribution. This refinement significantly reduces the tendency of martensite aggregation and coarsening, thus enhancing the cavitation performance of the coating.