Structure, phase composition, and properties of an Al-Hf alloy subjected to isentropic spherical shock waves

Abstract
The dimensions of characteristic zones of transformations related to the high-strain-rate deformation of the alloy in the solid state and its melting in stress waves, as well as partial evaporation of the shocked melt during unloading into the central cavity that is formed behind the front of a spherically divergent shock wave have been determined. The chosen regime of the explosive loading of the sphere led to melting at the isentrope and at the adiabat in shock waves in various zones along the radius, and to the subsequent formation of two zones with "cast" structures differing in the grain size, degree of supersaturation of the α-solid solution, and the size and shape of the precipitated aluminide particles. In the zone that undenvent melting and high-rate solidification, metastable aluminides A1₃Hf were revealed inside the adiabatic shear bands. The main features of the evolution of the structures of the matrix and the aluminides in the field of the solid-state transformation were revealed. As a result of high-rate loading and subsequent unloading, the brittle phase was shown to undergo fragmentation and fracture, while the aluminum matrix acquires the structure of a hot-worked material.