The analysis of the microstructure changes of a Fe–Mn–Al alloy under dynamic impact tests

We studied the changes in microstructures of a Fe–Mn–Al alloy with a composition of Fe–32 wt.% Mn–10 wt.% Al–1.07 wt.% C–0.36 wt.% Mo under dynamic impact tests. We carried out the impact tests in a split Hopkinson bar tester as well as a universal tensile tester. We controlled the tests at room temperature and the strain rates were 1 × 10−3, 1.2 × 103, 2.6 × 103, 4.1 × 103, 5.2 × 103, 7.3 × 103, and 8.0 × 103 s−1. After the impact tests, we analyzed the deformed specimens in a scanning electron microscope (SEM) and a transmission electron microscope (TEM). We correlated the mechanical properties with the changes in the microstructure of the Fe–Mn–Al alloy under impact tests at various strain rates. The ductile area decreased and the cleavage area increased as the strain rate increased. The dislocation density and twin density of the alloy increased when the strain rate increased. The strengthening of the alloy was more evident as the strain rate increased. The plastic deformation of the Fe–Mn–Al alloy was affected by the strain rates.