所谓扩散,常常是指原子(分子或离子)在气体、液体或固体解质中由热运动而引起的迁移现象。一滴黑墨水可染黑一杯清水,一打开氨气瓶就可闻到氨气的特殊气味,这都是人所共知的能直接观察或感觉得到的扩散现象。金属在热处理过程中也包含有扩散现象,不仅化学热处理有扩散而且其他热处理在加热、冷却过程中要发生相变也存在着 The so-called proliferation, often refers to the atoms (molecules or ions) in the gas, liquid or solid matter by the thermal movement caused by the migration phenomenon. A drop of black ink black water can be a cup of water, an ammonia gas cylinder can smell the special odor of ammonia, which are known to be directly observed or felt the proliferation phenomenon. Metal in the heat treatment process also includes a diffusion phenomenon, not only the proliferation of chemical heat treatment and other heat treatment in the heating and cooling process to phase change also exist