Brittle fracture resistance of the Fe–17%Ni alloy of extraterrestrial origin (the chinga meteorite) under static and dynamic loading

Abstract

The values of conditional yield strength, impact strength, and the parameters of static and dynamic crack resistance of the Chinga meteorite substance (the Fe–17%Ni alloy) are determined by mechanical testing for uniaxial tension and static bending and instrumented impact testing of V-notched prismatic samples at temperatures ranging between 20 and −196 °С. It is shown that the dynamic nature of material loading according to the three-point bending scheme contributes to a noticeable decrease in impact strength (KCV) and crack propagation energy (KCT) during low-temperature tests (−196 °С) and the appearance of brittle quasi-cleavage sites on the fracture surface. On the contrary, as the test temperatures decrease from room temperature to the temperature of liquid nitrogen during the static tests of the Chinga meteorite samples with induced cracks, the parameter of static crack resistance KC (K1C) increases and the fracture surface of the samples after low-temperature testing is characterized by predominantly viscous dimpled topography.