An unknown phase, which had been, detected in the aged LCN-155 type alloys and temporarily designated as “X”, was examined and discussions were made on the cor-relation with the additional elements such as C, N, Mo, W and Cb, the precipitate reaction in alloy during aging, the X-ray diffraction pattern, the lattice parameter, the specific gravity, and the chemical composition.
As the results, it was concluded that an unknown phase in the LCN-155 type alloys should be the new secondary phase unlike the well-known phases such as M23C6, M6C and η′ phase.
Further, a model of crystal structure was presented for the new phase. It was presumed that this phase, which was newly named as “π”, might be the carbo-nitride compound having the following crystal structure:
Space group……Fd 3 c
Unit cell dimension……a0=10·70-10·75Å
Number of atoms per unit cell……104
Chemical formula……M11 (C, N) 2
(Cr, Co, Ni, Fe) 8 (Mo, W) 3- (C, N) 2 in the LCN-155 type alloy.