Comprehensive study on scale-induced heterogeneity of (Ni2CrCo)94Nb3V3 high-entropy alloy variable-width thin-walled structure fabricated by additive manufacturing

Abstract

Laser additive manufacturing (AM) shows excellent advantages in near-net shape of complex parts. In this work, the (Ni2CrCo)94Nb3V3 high-entropy alloy variable-width thin-walled structures were fabricated by directed energy deposition, and its microstructure and mechanical properties at the narrow and wide ends were systematically studied in the printed and different heat treatment states. In the printed state, the 〈001〉 crystallographic orientation along the building direction and the 〈111〉 crystallographic orientation along the scanning direction are formed at the narrow and wide ends of the sample, respectively. The preferred crystallographic orientation is eliminated and numerous annealed twins are occurred at high-temperature annealing, while the original grain morphology and crystallographic orientation is not changed significantly after direct aging. In the printed state, the yield strength and ultimate tensile strength of the wide end are increased by 10.69 % and 11.60 % compared with that of the narrow end, and the elongation is decreased by 18.74 %. The differences in tensile properties at the narrow and wide ends of the sample are mainly related to the crystallographic orientation and dislocation density, without taking the statistically stored dislocations into account. The strength of both narrow and wide ends is significantly increased, but the difference in tensile performance between them is not changed through direct aging. In addition, the strength is slightly decreased and the difference in tensile properties between the narrow and wide ends is eliminated by high-temperature annealing. The results present in the current study provide new insights for the LAM optimizing design of thin-walled parts with complex structures.