EFFECT OF GRAPHITE ADDITION ON TENSILE PROPERTIES OF IN SITU SYNTHESIZED TITANIUM MATRIX COMPOSITES AT HIGH TEMPERATURE
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摘要: 利用钛与碳化硼及石墨之间的自蔓延高温合成反应经普通的熔铸工艺原位合成制备了不同摩尔比值TiB和TiC增强的钛基复合材料。测定了原位合成钛基复合材料的高温力学性能。结果表明:由于增强体的原位合成,复合材料的高温拉伸性能与基体合金比较有了明显的提高。高温拉伸断裂与温度有关,温度较低时,增强体断裂是材料失效的主要原因;而随着温度的提高,增强体与基体合金界面脱粘成为材料失效的主要原因。高温拉伸时裂纹容易在短纤维状增强体TiB的端面处形核与长大从而使增强体与基体合金脱粘导致材料失效,因此加入石墨形成更多的TiC粒子有利于提高复合材料的高温力学性能。Abstract: Titanium matrix composites reinforced with different mole ratios between TiB and TiC were fabricated by common casting technique utilizing the self-propagation high-temperature synthesis reactions between titanium and B4 C and graphite. The mechanical properties of the titanium matrix composites at high temperature were tested. The results show that tensile properties of the titanium matrix composites at high temperature are improved obviously due to the in situ synthesized reinforcements. Fracture mechanism is related to temperature. When the temperature is low, the fracture of reinforcement makes the composite failure. As temperature increases, the debonding between matrix alloy and reinforcement TiB conduces to the composites failure. Because the crack is likely to nucleate and grow on the end of TiB whiskers which makes the composites to failure, the addition of graphite forms more TiC particles and improve the mechanical properties of titanium matrix composites at high temperature.
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Keywords:
- in situ formation /
- titanium matrix composites /
- TiC /
- TiB /
- mechanical properties
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