Order-disorder fluctuations in alloys

How a material reacts to an external perturbation, like pressure or magnetic and electric fields, is predetermined by the thermal fluctuations of its local microscopic structure. While standard X-ray diffraction is insensitive to this fundamental phenomenon, synchrotron microbeams are able to detect hidden order-disorder fluctuations in metal alloys and explore their temporal correlations which show universal behaviour at phase transitions.

Probing a small volume (~1 μm³) of Fe₃Al close to the transition temperature (red curve), the measured diffracted intensity fluctuates strongly in time, while it is constant for temperatures far away from the transition temperature (blue curve).

Further information:

• Living metals
• Scaling in the Time Domain - Universal Dynamics of Order Fluctuations in Fe₃Al
  
• Ref.: C. Mocuta et al., Science 308, 1287 (2005).