The high entropy effect is the most important effect because it can enhance the formation of solid solutions and makes the microstructure much simpler than expected. The prior knowledge expected to multi component alloys to have many different interactions among elements and thus form many different kinds of binary, ternary, and quaternary compounds and/or segregated phases. Thus, such alloys would possess complicated structure brittle by nature. This expectation in fact neglects the effect of high entropy effect. Indeed, according to the Second law of thermodynamics, the state having the lowest mixing Gibbs free energy Δ Δ G m i x = Δ Δ H m i x − − T Δ Δ S m i x among all possible states would be the equilibrium state. Elemental phases based on one major element have small Enthalpy of mixing ( Δ Δ H m i x ) and a small Entropy of mixing ( Δ Δ S m i x ), and compound phases have large Δ Δ H m i x but small Δ Δ S m i x ; on the other hand, solid-solution phases containing multiple elements have medium Δ Δ H m i x and high Δ Δ S m i x . As a result, solid-solution phases become highly competitive for equilibrium state and more stable especially at high temperatures.