The Effect of Y₂O₃ on the Structure and Properties of Direct Laser Deposited Inconel 625 Super Alloy

Direct laser deposition Inconel 625 super alloy has important application prospects in the field of key parts preparation due to its good high temperature resistance. However, due to the easy formation of cracks and pores during the direct laser deposition, the high temperature service performance of the parts is difficult to meet the engineering needs. How to regulate the formation of the super alloy composition to eliminate defects and obtain fine grain strengthening effect so as to effectively improve the performance of the super alloy needs in-depth research. In this paper, to prevent super alloy from cracking, 0 wt.%, 0.5 wt.%, 1 wt.%, 2 wt.%, 2.5 wt.% Y 2 O 3 rare earth oxide were separately added in the Inconel 625 super alloy powder, and the Inconel 625 super alloys with high wear and oxidation resistance were prepared by direct laser deposition. The microstructure, hardness, wear resistance, oxidation resistance and crack elimination mechanism of laser deposited samples were studied. The results show that the samples with high hardness, wear resistance and oxidation resistance were successfully prepared using optimized parameters. It was found that Y 2 O 3 has obvious effect of refining structure, eliminating defects and enhancing the performance. The microstructure size of the sample with 0.5%Y 2 O 3 was obviously refined and reduced from the average size of 21 μm to 10 μm, the composition segregation was decreased, and the cracks and pores were obviously eliminated. In addition, a small amount of fine NbC carbides were precipitated at the grain boundaries to improve the hardness and wear resistance. The average hardness of the deposited sample with 0.5%Y 2 O 3 is up to 279 HV, and the wear rate of it was significantly higher than that of the deposited sample without Y 2 O 3 . The oxide film on the surface of the sample with Y 2 O 3 became more compact and the thickness of the oxide layer was smaller, which shows that it had a higher oxidation resistance at 750 °C. This work provides a useful reference for direct laser deposited Inconel 625 super alloy with high hardness, high wear resistance and high temperature oxidation resistance.