NUCLEATION AND EVOLUTION OF NANOPORES IN Fe95Ni05 ALLOY UNDER SHOCK LOADING

The nucleation and evolution of nanopores in monocrystalline and nanocrystalline Fe<sub>95</sub>Ni<sub>05</sub> samples with different grain size gradients and phase distribution over volume under shock loading were simulated. The grains of the nanocrystalline samples had the FCC structure and contained lamellae with the body-centered cubic (BCC) lattice. It was found that fewer nanopores were formed in a sample with a smaller grain size gradient. Samples with the same grain size gradient and a smaller volume fraction of lamellae had significantly lower damage both during shock loading and after relaxation. It was shown that the formation and development of nanopores always occurs at the junction of layers with different grain sizes along the intergranular boundaries, as well as at interphase boundaries inside the grains. The total volume of nanopores in monocrystalline samples was significantly less than in nanocrystalline ones. During loading, the face-centered cubic (FCC) fragments formed in BCC single crystals, and stacking faults and twins nucleated in FCC single crystals. Nanopores in single crystals nucleated as a result of the interaction of a reflected tensile wave with the fragment boundaries and structural defects.