Microstructural control for strengthening the γ-Fe/E21–(Fe, Mn)3AlCx alloys

We have proposed microstructural modification through lattice misfit control on the γ-Fe/E21–(Fe, Mn)3AlCx two-phase alloys, aiming for the improvement of mechanical properties. Since it is quite difficult to independently control lattice parameters of both γ-Fe and E21, we took the approach to educe the E21 lattice parameter based on two strategies, lowering carbon content in E21 by optimizing Al content of alloy composition, and the addition of Ni intending to reduce the phase stability of the E21 relative to the L12. The former attempt effectively decreases the lattice parameter of E21 and increases that of γ-Fe, by which lattice misfit is reduced. The latter idea is effective for reducing the lattice parameter of γ-Fe, while the lattice parameter of E21 slightly decreases only with the first 2 at.% Ni addition and remains almost constant. Consequently, lattice misfit increases, against our expectation.