Low stress grain boundary mediated plasticity and early fracture at basal twist grain boundaries in a titanium alloy

Titanium alloys are high-performance materials critical for demanding applications in aerospace, defense, and energy sectors. Basal twist grain boundaries were recently identified as key microstructure configurations leading to failures under different conditions. In the present study, we examined deformation and fracture in these specific locations to shed light on the mechanical behavior in relation to grain boundary characteristics. In situ characterization using high resolution digital image correlation was employed, and revealed both unexpectedly low stress deformation and early cleavage-like fracture. The collected dataset enabled the identification of influential grain boundary parameters, including their twist and tilt components. Molecular dynamics simulations of bicrystals subjected to shear loadings properly replicated experimental observations, and unveiled underlying mechanisms. The clarified influence of grain boundary characteristics on the mechanical response offers a new understanding of the detrimental role of basal twist grain boundaries on the performance of titanium alloys. Basal twist grain boundaries in titanium alloys were recently identified as key microstructure configurations that lead to mechanical failures in service. This study examines deformation and fracture in these specific locations to shed light on the mechanical behavior in relation to grain boundary characteristics.