Laser additive manufacturing of CrFeNb particles reinforced Ni-based superalloy composites with grain refinement and superior performance
Peixin Yang, Haijun Su, Quandong Hu, Yinuo Guo, Zhonglin Shen, Xiang Li, Hao Jiang, Minghui Yu, Xianbing Ji, Zhuo Zhang, Min Guo
Abstract
Laser power bed fusion (LPBF) as a widely used laser additive manufacturing, which has demonstrated a promising capability in the simultaneous formation of high-performance composites with unique microstructure. In order to further meet the urgent needs of aerospace sophisticated equipment, this work investigated the laser additive manufacturing of CrFeNb particles reinforced Ni-based superalloy composites with grain refinement and superior performance. A few CrFeNb particles were added to IN718 superalloy powder. The CrFeNb particles as a center of heterogeneous nucleation effectively facilitated to produce fine equiaxed grains and did not introduce significant residual stress in the as-deposited IN718 with CrFeNb composites. The stress concentration of the heat-treated IN718 with 4 wt% CrFeNb composites was significantly reduced. The grain orientation was not along the <001> and tended towards random. The particle size of as-deposited IN718 with 4 wt% CrFeNb composites was refined and the average size was 13.46 μm. The unmelted CrFeNb particles were dissolved and diffused into the γ matrix during heat treatment. A hard brittle phase was rich in Nb and Mo elements along the grain boundary. Under the combined effect of three strengthening mechanisms, the mechanical properties of the IN718 with 4 wt% CrFeNb composites at room temperature were improved. The yield strength, tensile strength and microhardness of the heat-treated IN718 with 4 wt% CrFeNb composites reached to 1194 MPa, 1426 MPa and 521 HV, respectively. This study provides a new method and foundation for the preparation and application of IN718 composites with excellent performance. Illustration of the synthesis of IN718/CrFeNb powder preparation process and strengthening mechanisms of IN718/CrFeNb composites fabricated by laser additive manufacturing. • The new CrFeNb is added to IN718 and high-quality composites are fabricated by LPBF. • The grain size of IN718 with 4 wt% CrFeNb is reduced from 17.54 μm to 13.46 μm. • The new phase of heat-treated IN718/CrFeNb composites is rich in Nb and Mo. • The IN718/CrFeNb composites present an excellent match with superior performance.