Dislocation flow turbulence simultaneously enhances strength and ductility

Area of Science:

• Materials Science
• Solid Mechanics
• Computational Materials Science

Background:

• Multi-principal element alloys (MPEAs) possess superior mechanical properties compared to conventional alloys.
• Dislocation dynamics are crucial for understanding deformation mechanisms in MPEAs.
• Conventional models often simplify the complex interactions within MPEAs.

Purpose of the Study:

• To investigate the fundamental deformation mechanisms in body-centered cubic MPEAs.
• To develop a discrete dislocation dynamics framework incorporating atomic lattice distortions.
• To elucidate the role of short-range ordering in dislocation motion.

Main Methods:

• Development of an atomic-lattice-distortion-dependent discrete dislocation dynamics framework.
• Integration of random field theory and a phenomenological dislocation model.
• Simulation of dislocation motions in body-centered cubic MPEAs.

Main Results:

• Identification of dislocation speed turbulence attributed to heterogeneous lattice strain fields from short-range ordering.
• Discovery that dislocation flow turbulence initiates dislocation multiplication.
• Observation that turbulence creates pinning sites, hindering dislocation movement.

Conclusions:

• Dislocation flow turbulence is a key mechanism in MPEAs, influenced by short-range ordering.
• This turbulence contributes to both strengthening and ductility, potentially resolving the strength-ductility trade-off.
• The developed framework provides insights into the complex deformation behavior of MPEAs.