A new strategy for fabrication of unique heterostructured titanium laminates and visually tracking their synchronous evolution of strain partitions versus microstructure

Abstract

• A new strategy for producing Ti laminates with gradient structure (GS) and heterogeneous lamella structure (HLS) is proposed. • Strain partitions versus microstructure evolution is visualized synchronously using ultrahigh-resolution SEM-DIC combined with EBSD. • GS/HLS Ti exhibited a superior combination of strength and ductility, which is attributed to HDI stress strengthening and HDI hardening. Heterostructured (HS) material with extraordinary mechanical properties has been regarded as one of the most promising structural materials. Here, we reported a new strategy for preparing heterostructured pure titanium laminates that possess a good combination of strength and ductility by combining gradient structure (GS) and heterogeneous lamella structure (HLS). The deformation characteristic versus microstructure evolution of GS/HLS titanium laminates, namely the strain partitions between different-sized grains (480–25 μm) was visualized using a scanning electron microscope (SEM) equipped with electron backscattered diffraction (EBSD) mode combined with the digital image correlation (SEM-DIC) with an ultrahigh spatial resolution for the first time. As a result, the hetero-deformation of unique GS/HLS structure by the characteristic of strain partitions could be accurately captured. While the hetero-deformation could result in the hetero-deformation induced (HDI) stress strengthening and HDI hardening, which were regarded as the key reason that the resulting GS/HLS Ti laminates showed a superior combination of strength and ductility. This could promote a more in-depth understanding of the strengthening-toughening mechanism of heterostructured material.