中文摘要：

采用真空自耗电弧熔炼法制备了母合金锭,分别在1400、1450、1500和1550℃下保温24h进行了热处理。采用光学显微镜、扫描电镜、能谱仪和X射线衍射仪对组织进行了观察和分析。结果表明：热处理后的组织仍然由（Nb,Ti）ss和（Nb,Ti）5Si3相组成。随着热处理温度的升高,大块六边形和板条状硅化物逐渐融解破碎成细小硅化物;共晶团中的片状（Nb,Ti）5Si3也逐渐球化和细化。经1450℃,24h热处理后,球化成颗粒状（Nb,Ti）5Si3的平均粒径最小,约为5μm。经1500℃,24h热处理后,组织有轻微的粗化现象,并且有孔洞出现。热处理后,颗粒状（Nb,Ti）5Si3中的Ti含量增加,而Nb含量减少。1450℃,24h是比较合适的热处理工艺。

英文摘要：

The master alloy ingot was prepared by vacuum consumable arc melting. Heat treatments were carried out at 1400, 1450, 1500 and 1550 ℃ for 24 hours, respectively. Both the arc-melted and heat-treated microstructures were investigated by optical microscope （OM）, scanning electron microscopy （SEM）, X-ray energy dispersive spectrum （EDS） and X-ray diffractometer. The results show that the heat-treated microstructure is still composed of （Nb,Ti）ss and （Nb,Ti）5Si3. With increase of temperatures for heat treatment, the hexagonal and strip-like （Nb,Ti）5Si3 blocks break gradually into small ones, and the （Nb,Ti）5Si3 slices in the eutectic microstructure change into particles. After heat treatment at 1450 ℃ , the average radius of the sphere-like （Nb,Ti）5Si3 particles is the smallest one about 5 μm. After heat treatment at 1500 ℃, the microstructure is slightly coarser and several holes appeare in the microstructure. Compared with the （Nb,Ti）5Si3 slices in the arc-melted eutectic colonies, the Nb content increase but the Ti content decrease in the spheroidized （Nb,Ti）5Si3 particles after heat treatments. The optimum heat treatment process is 1450 ℃ for 24 h for the composite materials.