Mechanical (compressive) form of driving force triggers the phase transformation from β to ω & α phases in metastable β phase-field Ti-5553 alloy

Most of the structural alloys' applications are under static, dynamic, and cyclic forms of loading. Ti-5553 alloy in the beta phase field is being investigated to confirm the mechanism of deformation and phase transformation upon quasi-static and dynamic compression. The Ti-5553 alloy was heat-treated at 900 degrees C (almost 50 degrees C above beta transus temperature) for one hour of soaking time followed by air quenching to achieve a fully beta phase field. After that, Dynamic compression (DC) by Split Hopkinson Pressure Bar (SHPB) and Quasi-static compression (QSC) were performed at a strain rate of (similar to)10(3)/s and 10(-3)/s, respectively. Recovered specimens were thoroughly examined by using different tools, such as an Optical microscope (OM), Scanning electron microscope (SEM), High-resolution transmission electron microscope (HRTEM), and Electron backscatter diffraction (EBSD) to get the reliable data for justification of logical conclusions. It is found that the dominating mode of deformation was dislocation slip along with twinning ({332} < 113 >) to some extent in both of QSC and DC, but sliding & spalling of the grain boundary is observed more in the former. Stress-induced phase transformation, i.e., beta to alpha '' and beta to omega, took place in the grains saturated with dislocation slips, where the former transformation occurred simultaneously with {332} < 113 > twinning, while beta to omega transformation was completed when a set of two adjacent (110)(beta) planes covered +/- 1/6th of the total separation distance between two (next to each other) (111)(beta) planes, by equal but opposite shear in (111)(beta) direction, and it caused 3% shrinkage of two closed packed (110)(beta) planes after transformation. (C) 2021 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

The study investigates the deformation mechanisms and phase transformations of Ti-5553 alloy under quasi-static and dynamic compression loading. It is found that dislocation slip and twinning are the dominating deformation modes, with grain boundary sliding and spalling more pronounced in quasi-static compression. Stress-induced phase transformations, such as beta to alpha'' and beta to omega, were observed in grains saturated with dislocation slips.