表面和界面效应对纳米晶粒尺寸的影响

应用热力学方法，讨论了非晶晶化法制取纳米晶体时所得最小晶粒与晶化温度的关系．发现当退火温度为物体熔点的1／2时，可制得最小晶粒，而在此温度下，过冷液体与晶体之间的Gibbs自由能之差达到最大值．考虑到样品较薄时较为明显的表面效应，计算了金属样品厚度对晶粒最小尺寸的影响．结果表明，晶粒的最小限度不仅受晶化过程中自由能差的影响，还与晶体厚度有关．样品厚度越小，对生成的最小晶粒尺寸影响越大．

Surface and interface effect on nano-grain size

It is found that the nano-crystalline materials obtained by crystallization from glass have the smallest grain size when the crystallization temperature is about half of the melting temperature, at which the Gibbs free energy difference between the under cooled liquid and the crystal reaches the maximum. The surface effect is considered simultaneously when the correlation thermodynamically between the free energy and the grain size is investigated. The result is that the thickness of samples plays a more important role in getting lower grain size when thinner materials are used.