The influence of process parameters and heat treatment on γ′ precipitates ofselective electron beam melted Ni-based single-crystal superalloy

γ′ precipitates, the main strengthening phase of Ni-based single-crystal superalloys, aredifficult to determine in the forming zone of selective electron beam melting (SEBM),which is best for realizing the direct manufacturing of single crystal superalloys.Herein, the relationship between parameters and γ′ precipitates is urgently needed to befabricated, and solution heat treatment is an efficient way to obtain a desired uniform γ′microstructure. In the initial work, an array of SEBM experiments with various processingparameters were carried out, the processing window and parameter influence on γ′precipitates were fabricated successfully, and a solution heat treatment protocol wasapplied for obtaining a homogeneous γ′ microstructure in the as-built SEBM microstructure.In processing, the bulks can be manufactured with a beam current of 10–12.4 mA and a scanspeed of 1.7–2.4 m/s. The dimensions of the γ′ precipitates present regular changes withparameters such as current and scan speed, and a great change had also been observed inbuilding height. After the heat treatment includes recovery-annealed (1100 °C, 6 h),solution-treated (1300 °C, 0.5 h), and aged (1100 °C, 6 h + 870 °C, 5 h) precipitates, thesize of γ′ precipitates gradually increases and homogenizes, and an optimized solution andaging heat treatment protocol was established.