To widen the applications of FeCoCrNi high-entropy alloys (HEAs) fabricated via selective laser melting, their mechanical properties must be improved, and annealing plays an important role in this regard. In this study, the microstructure, residual stress, and mechanical properties of the as-printed specimen and specimens annealed at 773–1573 K for 2 h were compared. As the annealing temperature increased, the specimen structure recrystallized from all columnar grains to equiaxial grains containing numerous annealing twins. The dislocation network, which formed during the solidification process under considerable shrinkage strain, decomposed into dislocations. The residual stress, yield strength, and hardness decreased, while the plasticity and impact toughness increased. During the deformation of as-printed and low-temperature-annealed specimens, the dislocation network remained unchanged and provided resistance to the dislocations moving within it, thus strengthening the specimen. The tensile strength remained largely unchanged owing to the reduction in the residual stress during low-temperature annealing, as well as the formation of the twinning network and dislocation wall under large deformation upon high-temperature annealing. Meanwhile, the ductility greatly increased, thus increasing the potential for industrial application of HEAs.

Effects of annealing on the structure and mechanical properties of FeCoCrNi high-entropy alloy fabricated via selective laser melting

Selective laser melting of Cu–Ni–Sn: A comprehensive study on the microstructure, mechanical properties, and deformation behavior

The effects of grain size, dendritic structure and crystallographic orientation on fatigue crack propagation in IN713C nickel-based superalloy

The evolution of geometrically necessary dislocations (GND) in aluminum was studied using high-resolution EBSD. Small grains had higher GND density than coarse grains and were most pronounced at a strain of ~9.8%, due to GNDs were more homogeneously organized at strain >9.8%. Furthermore, oriented grains with higher Taylor factor stored more GNDs than grains.

The grain size and orientation dependence of geometrically necessary dislocations in polycrystalline aluminum during monotonic deformation: Relationship to mechanical behavior

Microstructure evolution of annealed 7075 aluminum alloy and its influence on room-temperature plasticity

https://cronfa.swan.ac.uk/Record/cronfa48800/Download/0048800-12022019085531.pdf

Chris Deen

Papers

The dislocation behaviour and GND development in a nickel based superalloy during creep