机械合金化结合热压烧结制备(TiC+TiB_2)/Cu复合材料

Preparation of (TiC+TiB_2)/Cu Composites by Mechanical Alloying and Hot-press Sintering

通过对体系进行机械合金化,随后将其与Cu粉进行混合和热压烧结制备了(TiC+TiB_2)/Cu复合材料。研究表明,机械合金化促使B_4C粉末分解并向Ti粉末中的固溶形成Ti-C-B的三元混合体系,有效降低了体系的反应温度,并在随后的热压烧结中生成(TiC+TiB_2),其原因是在Ti-C-B体系中生成TiB_2相比TiB具有更低的吉布斯自由能变。当增强相含量较低时,强化相颗粒细小弥散地分布在铜基体中,且与基体界面结合良好,可显著提高复合材料的硬度;但随着含量的增加,强化相的团聚现象加剧,与基体的界面结合方式也转变为简单的机械包裹,其强化效应并不能得以体现。此外,由于机械合金化提高了体系反应的活性,有效地避免了Ti向铜基体中的固溶,当增强相的设计含量为15vol%时所制备的(TiC+TiB_2)/Cu复合材料与直接混合Cu-Ti-B_4C粉末制备的复合材料相比导电率大幅提升。

（TiC＋TiB2）/Cu composites were prepared by mixing and hot-press sintering Cu powder with mechanically alloyed Ti-B4C powder mixture. Results show that mechanical alloying can facilitate the decomposition of B4C and its solution into Ti powder to form a solution of ternary Ti-C-B system. Besides, on-set temperature of Ti-B4C in-situ reaction decreases and reaction products are TiC＋TiBz, because the formation of TiB2 has lower Gibbs free energy change than that of TiB. When the content of reinforcements is low, they are small and well-dispersed particles in the Cu matrix, and then the reinforcements and the matrix are well combined, which can significantly increase the hardness of the composites. As their content increases, reinforcements aggregate seriously, and the interface transfers into a simple mechanical package. When the designed content of reinforcements is 15vo1% , the electrical conductivity of the prepared （TiC＋TiB2）/Cu composites is 47.1%IACS, which is much higher than 12.46%1ACS of the composites prepared by non-milled Cu-Ti-B4C mixture, suggesting that mechanical alloying can accelerate reaction between Ti-BaC and orevent the solution of Ti into the Cu matrix.