STRUCTURAL PHASE TRANSFORMATIONS IN INTERMETALLIC NiAl UNDER UNIAXIAL HIGH-SPEED DEFORMATIONS IN THE ABSENCE OF ENERGY DISSIPATION

10.25712/ASTU.1811-1416.2025.01.011

Abstract

Using a computer experiment, the structural and phase transformations possible in the intermetallic compound NiAl 50% (at.) Al and 50% (at.) Ni under conditions of high-speed deformation at speeds exceeding the speed of sound of 5∙10⁹ s^-1 and 5∙10¹⁰ s^-1 were studied. The experimental conditions were set in such a way that no energy dissipation occurred in the unloading waves. The interactions between atoms in the alloy were specified in the approximation of the many-particle potential of Mishin et al. The single crystal was represented as a cube with an edge length of 57.6 Å with the orientation of the axes [100], [010], [001].  It is shown that uniaxial tension is accompanied by two phase transformations: BCC – BCC+FCC and BCC+FCC – FCC. During uniaxial compression, phase transformations BCC – BCC+HCP and BCC+HCP – HCP occur. Compression at 300 K at the last front, manufacturing defects with FCC interlayers. At higher temperatures, such defects do not form. As the deformation rate increases, the yield strength of the material increases. At all stages, deformation occurs according to a quasi-elastic mechanism. At transition stages, areas of plastic deformation are observed, but the movement of dislocations is carried out due to the applied external stress without the contribution of thermal vibrations of the lattice. At transition stages, areas of plastic deformation are observed, but the movement of dislocations is carried out due to the applied external stress without the contribution of thermal vibrations of the lattice.