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用真空非自耗电弧熔炼法制备了Nb-16Si-22Ti-2Hf-2Cr-2Al母合金锭,用Y2O3坩埚真空感应熔炼对母合金锭重熔,浇注在温度梯度约为4℃/mm的模壳里,制备出Φ60 mm×170 mm铸锭,研究了1500℃/100 h真空热处理后铸锭的组织特征对室温抗拉强度和高温压缩性能的影响。结果表明,真空感应熔炼Nb-16Si-22Ti-2Hf-2Cr-2Al合金经过1500℃/100 h热处理后,合金锭的组成相为NbSS枝晶,Nb5Si3层片或不规则颗粒和残留Nb3Si块。块状Nb3Si的尺寸越大,发生完全共析转变需要的时间越长、温度越高。热处理合金锭的室温抗拉强度在208~355 MPa之间,室温延伸率变化不大,均小于0.3%。残留的粗大块状Nb3Si和热处理过程中析出的HfO2是导致合金锭拉伸性能较低的重要原因。合金锭的高温压缩强度受到组织中硅化物相含量的影响,压缩强度与硅化物含量成正比。
The Nb-16Si-22Ti-2Hf-2Cr-2Al master alloy ingot was prepared by vacuum non-consumable arc melting method. The mother alloy ingot was remelted by vacuum induction melting with Y2O3 crucible. The master alloy ingot was remelted at a temperature gradient of about 4 ℃ / mm The Φ60 mm × 170 mm ingot was prepared and the microstructure of the ingot after 1500 ℃ / 100 h vacuum heat treatment was studied. The effects of the ingot on the room temperature tensile properties and the high temperature compressive properties were studied. The results show that the composition of the alloy ingot is NbSS dendrite, Nb5Si3 lamella or irregular grains and residual Nb3Si block after vacuum induction melting Nb-16Si-22Ti-2Hf-2Cr-2Al alloy after 1500 ℃ / 100 h heat treatment. The larger the size of the massive Nb3Si, the longer it takes for a complete eutectoid transformation to occur, the higher the temperature. The tensile strength at room temperature of the heat-treated alloy ingot is between 208 and 355 MPa, and the elongation at room temperature does not change much, both of which are less than 0.3%. The residual coarse Nb3Si and HfO2 precipitated during the heat treatment are the main reasons for the low tensile properties of alloy ingot. The high-temperature compressive strength of the alloy ingot is affected by the content of the silicide phase in the structure, and the compressive strength is directly proportional to the silicide content.