Heterogeneous structure and dynamic deformation of an equiatomic TiZrV medium-entropy alloy

The as-drawn equiatomic TiZrV medium-entropy alloy (MEA) has a diphasic heterostructure, and exhibits great potential for structural applications. The as-drawn TiZrV MEA is composed of two phases of the TiZr and TiV with body-centered cubic (BCC) structure, which mainly exist in the form of elongated grains with an average grain size of about 70 mu m. A small amount of the two phases embedded in each other's coarse grains in the form of submicron second phase particles, forming a diphasic heterostructure. The yield strength and compression ratio of the specimen subjected to thrice impacts can reach 1410 MPa and 39%, respectively, at a strain rate of 1100 s-1 and room temperature. After thrice impacts, about 3.5% by volume of the TiZr was observed to be uniformly distributed in the coarse grains of TiV phase in the form of second phase particles of about 43 nm. Precipitation strengthening and high-density dislocation strengthening based on its heterostructure are the main reasons for the improvement of mechanical properties of the TiZrV MEA. The average grain size of the outer and inner regions of the shear band formed by localized shear stress in the cylindrical specimen of TiZrV MEA is about 3.4 and 43 mu m, respectively. The TiZr and TiV are embedded in each other's coarse grains in the form of second-phase particles of about 35 and 175 nm, respectively, within the shear band. The rotational dynamic recrystallization (RDR) mechanism can simulate the process of ultra-fine grains in the shear band. The diphasic heterostructure in the shear band may be formed by the intergranular rotation of the grains under the action of shear stress.