Precision machining performance and mechanism of Ni/Ni3Al alloy under cryogenic temperature

Abstract

Nickel-based superalloys are extensively used in extreme environments due to their excellent mechanical properties, which are attributed to the large volume fraction of the γ' phase. However, the manufacturing process of these alloys is still challenging and can be improved by cryogenic machining. Despite numerous experimental studies on this topic, experimental methods are not sufficient to analyze the ultra-precision machining of Ni-based alloys at low temperatures. There is a lack of mechanistic understanding of the low-temperature nano-cutting process of Ni-based alloys. Thus, we performed a simulation analysis of cryogenic nano-cutting on a Ni/Ni3Al alloy using molecular dynamics (MD). We investigated the stability of cutting forces and microstructural evolution of this two-phase single-crystal alloy. We found that appropriate low temperatures can significantly improve the cutting performance of Ni/Ni3Al two-phase single-crystal alloy. Specifically, we found that the stability of cutting at 123 K is the best for workpiece A, while the cutting stability at 173 K is the best for workpiece B. Additionally, we calculated the machined surface roughness and precision. The minimum surface roughness is observed at 123 K in workpiece A, followed by 223 K. In workpiece B, the minimum roughness is observed at 223 K, while the roughness at 123 K is considerably higher compared to other temperature levels. This study outlines a reference method for determining the optimal temperature during the material removal process. This approach is significant as it helps in understanding the micro-removal mechanism of Ni-based alloys better.