Transonic dislocation propagation in diamond

Area of Science:

• Materials Science
• Solid Mechanics
• Crystallography

Background:

• Dislocation motion is key to material deformation.
• The maximum speed of dislocations remains an open question.
• Theoretical models suggest a limiting velocity, but transonics are possible.

Purpose of the Study:

• To experimentally investigate ultrafast dislocation motion.
• To determine if dislocations can exceed the speed of sound.
• To provide evidence for transonically moving partial dislocations.

Main Methods:

• Femtosecond X-ray radiography was employed.
• Tracking dislocation motion in shock-compressed single-crystal diamond.
• Visualizing the propagation of stacking faults.

Main Results:

• Observed stacking faults propagating faster than the slowest sound wave speed in diamond.
• Provided direct evidence of partial dislocations moving at transonic speeds.
• Demonstrated the possibility of exceeding the predicted limiting velocity.

Conclusions:

• Partial dislocations can move at transonic velocities.
• Experimental evidence supports the existence of transonically moving dislocations.
• Understanding dislocation mobility limits is vital for materials under extreme conditions.