中文摘要：

采用真空非自耗电弧熔炼法制备Nb—Ti-Si基超高温合金的母合金锭，分别于1300、1400、1500和1600℃保温50h，对其进行均匀化处理，然后于1100℃保温50h进行时效处理。结果表明：热处理后的组织主要由Nbss和（Nb、x）5Si3（x代表Ti、Cr和Hf元素）组成，经1600℃、50h和1600℃、50h＋1100℃、50h热处理后的组织中还出现HfO2。随着热处理温度的升高，多边形和板条状大块硅化物逐渐溶解或破碎成小块硅化物，残留的具有典型层片状或团状形貌的共晶组织的含量逐渐减少。1500℃、50h＋1100℃、50h是Nb—Ti—Si基超高温合金比较合理的热处理工艺。

英文摘要：

The master alloy ingot of Nb-Ti-Si based ultrahigh temperature alloy was prepared by vacuum nonconsumable arc melting. The coupons were homogenized at 1300, 1400, 1500 and 1600 ℃ for 50 hours respectively, and then aged at 1100 ℃ for 50 hours. The heat-treated microstructures were still composed of Nbss and （Nb, x）5Si3 （x represents Ti, Hf and Cr elements）. But after the heat treatments both at 1600 ℃, 50 h and 1600 ℃, 50 h＋1100 ℃, 50 h, HfO2 was found in the mucrostructure. With the increase of heat treatment temperatures, polygonal and plate-like big （Nb, x）5Si3is desolved gradually or broken into small ones, and the amount of retained typical lamellar or rod eutectic colonies reduced gradually. 1500 ℃, 50 h＋1100℃, 50 h is an optimum heat treatment process for Nb-Ti-Si based ultrahigh temperature alloy.