TiB_2晶须的自蔓延高温合成及其生长机理  

Self-propagating high-temperature synthesis and growth mechanism of TiB_2 crystal whiskers

作　　者：王明远[1] 李俊寿[1] 武小娟[1] 李苏[1] 赵芳[1] 

机构地区：[1]军械工程学院先进材料研究所,石家庄050003

出　　处：《粉末冶金材料科学与工程》2015年第4期522-526,共5页Materials Science and Engineering of Powder Metallurgy

基　　金：国家自然科学基金项目(51172281)

摘　　要：以Mg、B2O3、TiO2为原料,Cu2O为添加剂,采用自蔓延高温合成法制备TiB2粉体。研究添加剂Cu2O含量对TiB2晶体形态的影响,讨论TiB2晶须的生长机理。采用XRD、SEM分析合成产物的物相组成及微观形貌。结果表明:加入4%的Cu2O可生成大量高长径比的TiB2晶须,TiB2晶须的生长机制属于气-液-固(V-L-S)机制;首先Cu2O在高温下分解生成O2和Cu,O2向外喷射时形成的孔道为TiB2晶须的生长提供空间条件,自蔓延反应产生的高温为其提供能量条件,熔融态的Cu作为催化剂,与Ti形成以反应生成的TiB2为衬底的合金液滴,然后通过不断吸收Ti原子和B原子,使TiB2形核并定向生长,最终形成TiB2晶须。TiB2 powder was prepared by self-propagating high-temperature synthesis method using magnesium powder, boron oxide powder, titanium dioxide powder as raw materials and cuprous oxide powder as additive. The effect of CU2O content on the crystal morphology of TiB2 was studied and the growth mechanism of TiB2 crystal whisker was discussed. XRD and SEM were used to analyze phase composition and microstructure of synthesized powders. The experimental results show that a large amount of TiB2 crystal whiskers with high ratio of length to diameter are generated when 4% CU2O is added. The growth mechanism of TiB2 crystal whisker is Vapour-Liquid-Solid （V-L-S）. That is, at the high temperature Cu2O firstly decomposes into O2 and Cu, and the pore canal formed by O2 jetting provides space for the growth of TiB2 whisker while the high temperature formed by self-propagating reaction provides energy for it. Molten Cu, serving as catalyst, and Ti form alloy droplets with TiB2 generated as substrate. And then Ti atom and B atom are absorbed constantly to make TiB2 nucleate and grow directionally. Eventurally, TiB2 whisker is formed.

关 键 词：TIB2 SHS 晶须 生长机理 

分 类 号：TB333[一般工业技术—材料科学与工程]