Effect of elemental composition on phase formation during milling of multicomponent equiatomic mixtures

Using mechanochemical synthesis through milling of equiatomic multicomponent mixtures of Cr, Fe, Co, Ni, Al, Ti, Mo, and Nb metals in various combinations, we have synthesized powder alloys with different phase compositions: amorphous phase (AP), AP + BCC phase, AP + BCC phase + MO, and FCC + BCC phases. The FCC phase has been shown to be a Ni-based solid solution. The presence of aluminum in a starting mixture helps to stabilize the BCC phase owing to the formation of a disordered B2 phase. Al dissolves in both the BCC and FCC solid solutions, increasing their lattice parameters. In Al-free starting mixtures, Cr is responsible for the formation of the BCC solid solution. The formation of an AP during milling of multicomponent mixtures is favored by the presence of transition metals with a large atomic radius: Ti, Mo, and Nb.