Temperature dependence of mechanical properties of equiatomic NiCoCr medium-entropy alloy printed by selective laser melting
(1. College of Materials Science and Engineering, Hunan University, Changsha 410082, China;
2. Hunan Engineering Research Center of New Energy Vehicle Lightweight, Hunan Institute of Engineering, Xiangtan 411104, China)
2. Hunan Engineering Research Center of New Energy Vehicle Lightweight, Hunan Institute of Engineering, Xiangtan 411104, China)
Abstract: The effects of process parameters on the densification, microstructures, and mechanical properties, as well as the temperature dependence of the mechanical properties, of a NiCoCr medium-entropy alloy fabricated with selective laser melting were studied. The results indicate that the microstructures and mechanical properties are not linearly related to the volume energy density (VED) but are affected by the scanning speed and laser power. The optimal process parameters are identified as a scanning speed of 800 mm/s and a laser power of 250 W, while the VED is only 57 J/mm3 lower than the highest value of 68 J/mm3. The yield strengths of the optimal sample are ~819, ~709 and ~618 MPa at 77, 200, and 293 K, respectively. The temperature dependence of the mechanical properties is determined and verified by the experimental results.
Key words: selective laser melting; medium-entropy alloy; NiCoCr; cryogenic temperature; mechanical properties