Ti-45Al合金的定向凝固组织

Directionally Solidified Microstructures of Ti-45Al Alloy

采用区域重熔定向凝固技术制备了Ti-45Al合金定向凝固试样,研究了不同参数下的凝固组织。结果表明,该合金在定向凝固过程中一次凝固可以以胞晶形式实现定向生长,胞晶内α2/γ片层方向与生长方向成45°或90°。凝固过程中稳定相β及亚稳相α同时存在,并以胞状生长,存在竞争而引起的交替现象。降速生长时定向组织比较理想。淬火实验表明,在大过冷度下亚稳α相作为领先相析出。

The directionally solidified samples of Ti-45A1 were prepared with zone-melting directional solidification technique. The macro and microstructures were investigated by optical microscopy. The results show that the crystals grow in cellular form. The primary phases can be beta (stable phase) and/or alpha (metastable phase). The angle between the lamellar boundaries in the cellular grains and the growth direction is either 45 degrees or 90 degrees. The directional structure of sample grown with decreasing growth rate is better than that with increasing growth rate. The microstructures in the quenched samples show that the metastable phase can grow firstly as leading phase.