Elastic constants C₁₁, C₁₂, and C₄₄ for the selected systems. The systems are classified into four categories: (a) NiCo solutions including paramagnetic (PM) and ferromagnetic (FM) states, (b) (Ni, Co)₃X including (Ni, Co)₃Al, (Ni, Co)₃W, (Ni, Co)₃Ti and all binary systems, (c) other ternary systems including W or Ti elements, and (d) quaternary systems. The vertical ordinate in this figure (Co, W, and Ti concentrations) increases in each system, and in panel (d) the W/Ti concentration changes first and then the Co concentration changes.