Simultaneous IR and time-resolved X-ray diffraction measurements for studying self-sustained reactions.

Area of Science:

• Materials Science
• Solid State Chemistry
• Advanced Materials Synthesis

Background:

• Self-propagating high-temperature synthesis (SHS) is a key method for producing advanced materials like ceramics, composites, and intermetallics.
• Understanding the in situ reaction mechanisms and thermal evolution is crucial for optimizing SHS processes.

Purpose of the Study:

• To investigate the structural transformations and thermal evolution during self-propagating high-temperature synthesis.
• To elucidate the reaction pathways and intermediate phases formed during the synthesis of advanced materials.

Main Methods:

• Utilized time-resolved X-ray diffraction with a synchrotron beam (D43 beamline, LURE, Orsay).
• Employed simultaneous infrared (IR) thermography for in situ temperature monitoring.
• Achieved short acquisition times (30 ms per pattern) for high temporal resolution.

Main Results:

• Observed distinct reaction steps, including aluminum melting and rapid reactions between aluminum (Al) and nickel (Ni).
• Identified the formation of Ni and AlNi phases, with other compositions remaining liquid.
• Described the formation of FeAl, noting a phase transition in iron stabilizing the reaction at approximately 1173 K.
• Confirmed that aluminum melting preserves the nanostructure induced by mechanical activation in the final product.

Conclusions:

• The study provides detailed insights into the complex mechanisms of SHS.
• The findings contribute to the understanding and optimization of advanced material production using SHS.
• In situ monitoring techniques are effective for characterizing rapid synthesis reactions.