热处理对快速凝固Ti-48Al-4Cr合金组织影响规律研究

Effect of heat treatment on microstructures evolution of rapidly solidified Ti-48Al-4Cr alloy

摘要:

采用单辊旋淬快速凝固设备制备了Ti-48Al-4Cr(at.%)薄带，并在真空封装后进行热处理实验，研究热处理对快速凝固Ti-48Al-4Cr合金的组织演变规律。结果表明，快速凝固Ti-48Al-4Cr合金凝固基体为等轴的γ相，基体中含有少量的B2相、α2相颗粒和片层组织；经723℃保温1h空冷后，亚稳的α2相颗粒失稳，但片层组织仍然比较稳定；热处理温度升高至932℃时，片层组织中的杆状α2相开始按照瑞利分解失稳，分解成大量短杆状或者颗粒状的α2相；在995℃保温1h以后，基体中已较难发现片层组织存在，但存在着排列方向相同的棒状α2相，同时在等轴γ相晶界处发现了数量较多的颗粒状B2相。本论文的研究为进一步研究快速凝固条件下的TiAl金属间化合物的组织与相转变提供了基础，丰富了快速凝固理论。

Abstract:

In this work the effect of heat treatment on microstructure of Ti-48Al-4Cr(at.%) alloy rapidly solidified at the wheel speed of 10m/s were experimentally investigated by using the single roller melt-spinning technique. The results indicate that after rapid solidification, the microstructures mainly consist of equiaxed γ phase, few volume fraction of α2, B2 phase particles and lamellar structures exists in the γ phase matrix. After heat treament at 723℃/1h, α2 particles becomes unstable. Annealing at 932℃ for 1h, the α2 plate in lamallar strucctures becomes unstable. The α2 plate in the lamellar structures is subdivided into rod-shaped α2 phase and α2 particles. Annealing at 995℃/1h, large volume fraction of lamellar structures dissolved, however, rod shaped α2 phase still exists. B2 phase is being precipatated at the grain boundary. This research has provided the basis of further studying on the microstructures and phase transformation of rapidly solidified Ti-Al intermetallics and enriched the theory of rapid solidification.