ナノ粒子系2元合金状態図をバルクの熱力学量と表面張力を用いて評価する計算手法と計算例を紹介した。粒子径が小さくなると，純成分の融点は下がり，液相線温度も低下し，さらに固溶体の組成域が拡大する傾向を示した。平衡状態図の粒子径依存性は固相および液相において過剰自由エネルギーが正の大きな値を示す合金系において顕著に現われることが明らかとなった。
Binary phase diagrams of nano-particle alloy systems have been evaluated from the information on the Gibbs energy and the surface tension of bulk systems. As the size of a particle decreases, the melting point of pure component decreases and the liquid phase region is enlarged in binary phase diagrams, in other words, the liquidus temperature decreases. In addition, solid solutions in nano-particle systems have larger composition ranges than those in bulk alloys. It is found from the above evaluation that the size dependence of a particle on phase diagrams is remarkable when excess Gibbs energies have large positive values in solid and liquid phases.
