Recently, we predicted a mechanism of solid-solid phase transformation (PT) via virtual melting at 121K below the melting temperature. We report additional experimental and theoretical results for PTs among three polymorphs of the energetic material HMX, α, β, and δ that support this mechanism. In particular: (a) the predicted velocity of interface propagation for β→δ PT and overall kinetics of δ→β PT are in agreement with experiment; (b) the energy of internal stresses is sufficient to reduce the melting temperature from 520to400K for δ→β PT; (c) the nanocracking that appears during solidification does not change the PT thermodynamics and kinetics for the first and the second β↔δ PT cycles; (d) δ→β PT starts at a very small driving force; (e) δ→α and α→δ PTs do not occur above 400K and below 461K, respectively.
- Center for Mechanochemistry and Synthesis of New Materials
Available at: http://works.bepress.com/valery_levitas/36/