Unexpected dynamic transformation from α phase to β phase in zirconium alloy revealed by in-situ neutron diffraction during high temperature deformation

Dynamic transformation from alpha (HCP) to beta (BCC) phase in a zirconium alloy was revealed by the use of in-situ neutron diffraction during hot compression. The dynamic unexpectedly detected isothermal compression at temperatures 900°C and 950°C (alpha + two-phase region) strain rates 0.01 s−1 0.001 s−1, even though equilibrium states were achieved prior accompanied diffusion Sn phase, which resulted changes lattice parameters characteristic microstructure grains. constant measured increased compression, while exhibited an initial increase subsequent decrease As result, magnitude (elastic) as well stress (elastic stress, or stress) found become much greater than those phase. According atomistic simulation, Gibbs free energy with hydrostatic compressive pressure more evidently that It could be concluded such results occurrence is attributed relative owing difference stress; i.e., larger distortion made thermodynamically unstable present result suggests deformation materials can dynamically make plastically harder higher softer through increasing elastic might lead phase.Download : Download high-res image (144KB)Download full-size