锂硼合金反应合成机制  

Modeling of reaction synthesis for Li-B alloys

作　　者：刘志坚[1] 曲选辉[1] 李志友[1] 黄伯云[1] 

机构地区：[1]粉末冶金国家重点实验室,湖南长沙410083

出　　处：《粉末冶金材料科学与工程》2002年第3期185-192,共8页Materials Science and Engineering of Powder Metallurgy

基　　金：国家自然科学基金(50172062);教育部高等学校骨干教师资助计划项目

摘　　要：提出了锂硼合金反应合成的物理模型,反应过程中有2次放热反应,第1次放热反应分成3个阶段:第1阶段为Li与B粒在界面(～330℃)的瞬时反应,此放热量与B粒的半径成反比;第2阶段为Li液通过附着在B粒表面LiB_3中的扩散而与内核B的反应,此过程可用固体反应中的金斯特林格模型来描述,其反应速率常数与B粒的半径平方成反比;第3阶段是在425℃以上将LiB_3溶解到Li液体中,但与此同时,第2次放热反应也在开始进行。第2次放热反应通过Li-B化合物的形核和长大来完成,它分成形核孕育和爆发反应2个阶段。有足够形核数目时,产生爆发性反应。温度越低,产生爆发性反应所需时间越长。运用该模型解释了合成实验中出现的现象。The modeling of reaction synthesis for Li-B alloys has been proposed. There are two exothermal reactions in the course of synthesis. The first exothermal reaction can be divided into three stages. The first stage is an instantaneous reaction on the boundary between boron particles and lithium melting. The caloric released in this stage is inversely proportional to particle size of boron powder. The second stage is a reaction between boron in the core of the particle and the lithium that have to diffuse through the product LiB_3 on the surface of the boron particle. This process can be described by Joneston L G model in solid state reaction, and is closely related to the particle size. When the temperature is up to 420℃, the product LiB_3 dissolves in Li liquid. That is the third stage of the first exothermal reaction. At the same time, the second exothermal reaction begins. The second exothermal reaction is completed through nucleation and growth of the last Li-B compound. It can be divided into two stages, they are the nucleation pregnant stage and the exploded reaction stage. When the number of the particle nucleated is enough, the exploded reaction takes place. The lower the temperature, the longer the time needed to lead exploded reaction. By means of the model promoted, the experimental phenomena in the synthesis have been explained.

关 键 词：锂硼合金 反应合成 模型 热电池 

分 类 号：TG111.5[金属学及工艺—物理冶金]