2024/06/13 by Valery I. Levitas, Levitas, Valery I., Raghunandan Pratoori +7 · 1 citation
Materials Science · Physics and Astronomy · #Metal Alloys Wear and Properties #Force Microscopy Techniques and Applications #High-Velocity Impact and Material Behavior
paper · pdf · doi:10.48550/arxiv.2406.09461
Significant grain growth is observed during the high-pressure phase transformations (PTs) at room temperature within an hour for various materials. However, no existing theory explains this phenomenon since nanocrystals do not grow at room temperature even over a time span of several years because of slow diffusion. Here, we suggest a multistep mechanism for the grain growth during α→ω PT in Zr. Phase interfaces and grain boundaries (GBs) coincide and move together under the action of a combined thermodynamic driving forces. Several intermediate steps for such motion are suggested and justified kinetically. Nonhydrostatic stresses due to volume reduction in the growing ω grain promote continuous growth of the existing ω grain instead of a new nucleation at other GBs. In situ synchrotron Laue diffraction experiments confirm the main predictions of the theory. The suggested mechanism provides a new insight into synergistic interaction between PTs and microstructure evolution.