机械合金化制备纳米ZrB2-TiB2复合粉末

ZrB2-TiB2 nanocomposite powder fabricated via mechani-cal alloying

摘要:

本文采用Zr、Ti、B为原料（摩尔比：1:1:4），在氩气气氛保护下，采用机械合金化方式，在球料比10:1、球磨转速500 rpm实验条件下制备了纳米结构的ZrB2-TiB2。文章采用X射线衍射仪（XRD）、场发射扫描电镜（FESEM），透射电镜（TEM）仪器，对不同球磨时间粉末的相组成、微观结构进行了表征。结果发现，原始粉末经120小时球磨后，粉末主要由ZrB2和TiB2组成，平均尺寸再20纳米左右，TiB2 分布于ZrB2基体上。文章还探讨了该体系获得目标产物的机械合金化机制。

Abstract:

Diborides, including zirconium diboride (ZrB2) and titanium diboride (TiB2), have a number of desirable ceramic qualities that make suitable for preparing ceramic-matrix composites. However, synthesizing a composite based on these materials frequently requires high temperatures and complex synthetic methods. In this study, a nanocrystalline ZrB2-TiB2 powder was synthesized via mechanical alloying (MA) of mixture of elemental Zr, Ti, and B powders mixed at a Zr/Ti/B mole ratio of 1:1:4, a 10:1 ball-to-powder weight ratio, and 500 rpm rotational speed in a planetary ball-mill under argon atmosphere using a ZrO2 vial and balls. MA has the benefits of low-cost, simplicity and high throughputs. The effect of milling time on the phase change was investigated by X-ray diffraction (XRD), and the microstructure development of the powder mixture was monitored by field emission scanning electron microscopy (FESEM) and transmission electron mi-croscopy (TEM). It was found that after 120 h of milling, a nanoscale composite powder with a ~20 nm mean particle size was obtained. Moreover, the TEM examination clearly showed the composite formed between the nanoscale TiB2 and ZrB2 particles. Finally, the milling mechanism was discussed, illustrating the time needed to initiate the reaction and when the fine, homogenous final composite was produced.