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为了研究高温均匀化及时效热处理对Nb-Ti-Cr-Si基超高温合金显微组织的影响,对样品进行均匀化处理,于1200-1500°C保温24h,随后于1000°C保温24h进行时效。结果表明,热处理后的组织主要由Nbss、(Nb,X)5Si3和Cr2Nb组成。随着均匀化处理温度的升高,电弧熔炼态的树枝状Nbss转变为等轴状,原先花瓣状的Nbss/(Nb,X)5Si3共晶组织消失,转变为分布于Nbss基体上的小块状(Nb,X)5Si3组织。Cr2Nb的形貌随均匀化处理温度的升高而发生明显变化。当均匀化处理温度达到1300°C以上,原先粗大的Cr2Nb发生溶解,在随后的冷却过程中在Nbss基体上沉淀析出细小、密集的针状Cr2Nb。经高温均匀化和时效复合处理后,Nbss基体上析出更为细小、密集的沉淀相Cr2Nb,使得Nbss、(Nb,X)5Si3和Cr2Nb相中Ti、Hf和Al元素的含量差别缩小。
In order to study the influence of high temperature homogenization and aging heat treatment on the microstructure of Nb-Ti-Cr-Si based superalloy, the sample was homogenized, incubated at 1200-1500 ° C for 24h, then incubated at 1000 ° C for 24h aging. The results show that the microstructure after heat treatment mainly consists of Nbss, (Nb, X) 5Si3 and Cr2Nb. As the homogenization temperature increases, the dendritic Nbss transformed into an equiaxed shape in the arc-melting state, and the originally petal-shaped Nbss / (Nb, X) 5Si3 eutectic structure disappears and turns into small pieces distributed on the Nbss matrix Like (Nb, X) 5Si3 organization. The morphology of Cr2Nb changes obviously with the increase of homogenization temperature. When the homogenization temperature reaches above 1300 ° C, the originally coarse Cr2Nb dissolves and precipitates fine, dense acicular Cr2Nb on the Nbss matrix during the subsequent cooling. After the homogenization and aging treatment, the more fine and dense precipitated phase Cr2Nb precipitated on the Nbss matrix, and the content of Ti, Hf and Al in the Nbss, (Nb, X) 5Si3 and Cr2Nb phases decreased significantly.