A new high-strength spinodal alloy

Preliminary investigations of a new high-strength alloy of composition Fe30Ni20Mn25Al25 (at.%) are described in this paper. The as-cast alloy consisted of a periodic two-phase microstructure of interconnected, similar to 50-nm-wide rods with fully coherent {100} interfaces, strongly suggestive of formation by a B2 to [(B2 + body-centered cubic (bcc)] spinodal decomposition. The (Ni,Al)-rich B2 and (Fe,Mn)-rich bcc phases differed in lattice parameter by <0.5%. Hardness and yield strength of the as-cast alloy were found to be approximately 500 VPN and 1500 MPa, respectively, and increased by more than 50% after annealing at 550 degrees C for several days. (Fe,Mn)-rich precipitates with a beta-Mn structure were observed in the annealed material.