Tensorial stress-plastic strain fields in $\alpha$-$\omega$ Zr mixture, transformation kinetics, and friction in diamond anvil cell

Various phenomena (phase transformations, chemical reactions, and friction) under high pressures in diamond anvil cell are strongly affected by fields of all components of stress and plastic strain tensors. However, they could not be measured. Even measured pressure distribution contains significant error. Here, we suggest coupled experimental-analytical-computational approaches utilizing synchrotron X-ray diffraction, to solve an inverse problem and find all these fields and friction rules before, during, and after $\alpha$-$\omega$ phase transformation in strongly plastically predeformed Zr. Due to advanced characterization, the minimum pressure for the strain-induced $\alpha$-$\omega$ phase transformation is changed from 1.36 to 2.7 GPa. It is independent of the compression-shear path. The theoretically predicted plastic strain-controlled kinetic equation is verified and quantified. Obtained results open opportunities for developing quantitative high-pressure/stress science, including mechanochemistry, material synthesis, and tribology.