Dynamic strain aging in biomedical Co-Cr-Mo-based alloys with nitrogen doping

摘要

The plastic deformation behavior of a biomedical Co-29Cr-6Mo-0.2N (wt.%) alloy with a fully γ (fcc) matrix was studied by compression tests from room temperature to 1073 K. Serrated stress-strain curves caused by dynamic strain aging (DSA) was clearly observed at temperatures of 773-973 K at a strain rate of 10~(-4) s~(-1). Such a flow behavior was not observed significantly in other conditions. Electron backscatter diffraction (EBSD) analysis revealed that deformation microstructures with DSA occurrence exhibited a large lattice distortion over the grains, while local strain preferentially increased in the vicinity of grain boundaries in the specimen deformed at room temperature. Dislocations were dissociated into stacking faults (SFs) bounded by Shockley partial dislocations both before and after deformation;;the DSA observed in this alloy would originate from the interactions between nitrogen atoms and the partial dislocations/SFs.