摘要
通过工艺试制总结出一套制备大规格高Nh—TiAl合金铸锭的工艺路线，并对铸锭轴向、径向成分进行检测分析，观察其显微组织。结果表明：采用三次真空自耗熔炼，熔速控制在4-5kg／min，补缩时慢速降电流即可获得理想的Ф220mm高Nb-TiAl合金铸锭；Al元素沿铸锭径向在1／2R处含量最高，表现出沿凝固方向低一高一低的变化规律，沿铸锭轴向Al元素含量从底部到顶部依次减小；Nb元素含量沿铸锭径向从边缘、1／2R处和中心处逐渐降低，沿铸锭轴向Nb元素含量从底部到顶部也依次减小；高Nb—TiAl合金铸锭边缘处得到细小的近片层组织，1／2R处和芯部晶粒充分长大得到较为粗大的片层组织。
A set of the preparation of large size high Nb-TiAl alloy ingot casting process was summarized by the trial process. The axial and radial components of ingot were analyzed, and the microstructure was observed. The results in detail are as follow： the ideal Ф 220 mm high Nb-TiAl alloy ingot can be obtained by the three times of vacuum consumable melting, and melting speed control in 4-5 kg/min, and slow feeding when the downhill current. In the transverse sections, the content of Al is at the highest level in the place of 1/2R, and the change law of low--high-- low along the solidification direction is shown. Along the longitudinal sections, the content of AI is gradually decreased from the bottom to the top of the ingot. In the transverse sections, the content of Nb is gradually decreased from the edge to 1/2R and radial zone of the ingot, and the segregation law of Nb is gradually decreased from the bottom to the top of the ingot. The fine and near the tissue layers can be obtained at the edge of High Nb TiAl alloy ingot, however, the grain fully grown more coarse lamellar microstructure at 1/2R and core of High Nb TiAl alloy ingot.
