Influence of Cu addition on the self-propagating high-temperature synthesis of Ti5Si3 in Cu–Ti–Si system
Influence of Cu addition on the self-propagating high-temperature synthesis of Ti5Si3 in Cu–Ti–Si system
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DOI：
10.1016/j.matchemphys.2008.04.047
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发表时间：
2008-10
影响因子：
4.6
通讯作者：
H. Y. Wang;S. Lü;M. Zha;Shujia Li;C. Liu;Q. Jiang
中科院分区：
文献类型：
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作者：
H. Y. Wang;S. Lü;M. Zha;Shujia Li;C. Liu;Q. Jiang
在Cu添加量为10- 50 wt.%的Cu-Ti-Si体系中，产物仅由Ti_5Si_3和Cu相组成，无过渡相。在Ti-Si体系中，合成的Ti 5Si 3颗粒大多呈多边形粗糙外观，具有明显的烧结形态。当Cu含量从10重量%增加到50重量%时，而Ti 5Si 3呈鹅卵石状，表面相对光滑，平均尺寸从15 μ m减小到12 μm以下，Cu-Ti-Si体系中Ti 5Si 3的形成机制为固溶-反应-沉淀过程。此外，Cu的添加对绿色坯体和反应后的坯体之间的体积变化有很大影响。体积变化随Cu含量从0增加到20 wt.%而增加，在20 ~ 50 wt.%范围内，随着含量的进一步增加而降低。在差示扫描量热过程中，Cu的加入显著降低了反应的起始温度，甚至远低于Ti的α→β转变温度（882°C），表明Cu的加入可以大大促进反应。因此，Cu的作用不仅作为稀释剂，而且作为反应物，参与自蔓延高温合成反应过程。
The self-propagating high-temperature synthesis (SHS) reactions can take place in Cu–Ti–Si systems with Cu additions of 10–50wt.%, and the products only consist of Ti5Si3and Cu phases, without any transient phase. In Ti–Si system, most of the Ti5Si3grains synthesized exhibit the polygon-shaped coarse appearance with an obviously sintered morphology. When Cu content increases from 10 to 50wt.%, however, the Ti5Si3exhibits cobblestone-like shape with a relatively smooth surface, and its average size decreases significantly from ∼15 to ∼2μm or less. The formation mechanism of Ti5Si3in Cu–Ti–Si system is characterized by the solution, reaction and precipitation processes. Furthermore, the addition of Cu has a great influence on the volume change between green and reacted preforms. The volume change increases with Cu content increasing from 0 to 20wt.%, and then decreases with the content further increasing from 20 to 50wt.%. The addition of Cu to Ti–Si system significantly decreases the onset temperature of the reaction during differential scanning calorimetry process, which is even much lower than the α→β transition temperature of Ti (882°C), suggesting that the reaction could be greatly facilitated by Cu addition. As a result, the role of Cu serves not only as a diluent but also as a reactant and participates in the self-propagating high-temperature synthesis reaction process.