Temperature Induced Displacive Structural Transformations

Martensitic transformation at low temperatures.

Cubic iron-nickel alloy nano-particles (only half of the sample is shown in order to see the interior) undergo a martensitic transformation (first movie) from the high temperature fcc austenitic phase (red) into the low temperature bcc martensitic phase (green) (due to technical reasons the surface is green or blue depending on the orientation of the surface). The heterogeneous nucleation starts at defects like corners and grows into the interior of the nano-particle with a fraction of the sound velocity (that is, the growth velocity depends on the crystallographic direction.) with a transient mixed phase region having a needle-like pattern. The final structure is twinned and can undergo a transformation back to the original austenite structure (second movie). The sample contains one million atoms (edge length=24nm) and was simulated for 67.5ps.

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Tags:

• Temperature
• Induced
• Displacive
• Structural
• Transformations