【摘要】 振动激发金属液形核技术特征是:当一种振动冷却棒插入金属液内时,棒体表面将迅速形成大量的细小晶粒,这些晶粒可被连续不断地弹射至金属液中,成为凝固过程中等轴晶的形核核心。采用30%氯化铵水溶液进行了物理模拟实验,探讨了振动激发金属液形核过程机理,结果表明:振动激发形核过程中产生的晶粒始于晶核发射器棒体与氯化铵水溶液之间的接触界面;振动和冷却促进了溶液表面结晶雨的形成;为了防止凝固坯壳在棒体表面快速长大,应通过对振动和冷却工艺进行控制,确保棒体表面的温度介于溶液的固、液相线温度之间,从而促进晶体的游离。更多还原

【Abstract】 The feature of nucleation in liquid metal excited by vibration was as follows: large number of fine crystallittes are formed on the surface of a vibrating and cooling bar inserted into liquid metal.The crystallittes are ejected to molten metal continuously and served as nucleus of equiaxed grain during solidification.Physical simulation was carried out with 30% NH4Cl aqueous solution.The original position of nucleation in liquid metal excited by vibration was discussed.The results show that the crystallittes are formed on the interface between crystal nucleus projector and NH4Cl aqueous solution.Vibration and cooling promote the formation of crystalline rain.The temperature of the crystal nucleus projector surface should be between the liquidus and solidus in order to make the crystalline nucleus leave and prevent growing up of solidified shell on the surface of crystal nucleus projector by controlling the vibration and cooling.更多还原